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Voltage‐Gated Proton Channels

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Abstract

Voltage‐gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely, the mechanism by which voltage‐dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage‐sensing domain of most other voltage‐gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single‐channel conductance approximately 103 times smaller than most ion channels, voltage‐dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH‐dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B‐cell receptor mediated responses in B‐lymphocytes. The most elaborate and best‐established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. © 2012 American Physiological Society. Compr Physiol 2:1355‐1385, 2012.

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Figure 1. Figure 1.

Voltage‐gated proton channels trigger the bioluminescent light flash in dinoflagellates. The proton concentration is high in the flotation vacuole (below the membrane in the diagram). An action potential depolarizes the membrane, opening proton channels, allowing protons to flow down their electrochemical gradient into the interior of the scintillon (upper compartment). The sudden drop in pH in the scintillon triggers the flash by two concerted mechanisms. Upon protonation, the light‐emitting pigment, luciferin (LH2) is released from luciferin‐binding protein (LBP) making it available as a substrate for luciferase, which is itself activated by acidification. [Adapted, with permission, from reference . Originally published in Bioluminescence in Action, edited by P. Herring, Academic Press, London. pp. 129‐170, 1978. Copyright Elsevier.]

Figure 2. Figure 2.

Membrane topology of voltage‐gated K+ channels (left), voltage‐gated proton channels (center), and voltage‐sensitive phosphatases (right). The K+ channel (lower panel) is a tetramer of the six transmembrane domain monomer shown in the top; the proton channel is a homodimer of the four transmembrane domain monomer in the top panel, and the phosphatase is a monomer. The assembled K+ channel has a single conduction pathway, but the proton channel has two, one in each protomer. The voltage‐sensing phosphatase (VSP) senses voltage, but does not conduct. The proton channel cartoon illustrates schematically that the dimer is held together by C‐terminal coiled‐coil interactions, and that the channel can be phosphorylated at Thr29 in the intracellular N terminus to produce the enhanced gating mode (cf. Figure 20). [Figure adapted, with permission, from reference . Originally published in Physiology 25:27‐40, 2010.]

Figure 3. Figure 3.

A phylogenetic analysis showing evolutionary relationships among 37 putative HV1 voltage‐sensing domain (VSD) sequences. This maximum likelihood phylogenetic tree with 100 boostraps was constructed from a multiple sequence alignment of the VSD portion of 37 HV1s; N‐ and C‐termini were truncated. Branch lengths are displayed to scale, and are proportional to the evolutionary distance between sequences. Bootstrap values greater than 60 are shown. [Figure adapted, with permission, from reference . Originally published in Proc. Natl. Acad. Sci. U S A. 108:18162‐18168, 2011.].

Figure 4. Figure 4.

Comparison of gating kinetics of the human proton channel dimer (A) and monomer (B), expressed in HEK‐293 cells. Note the slower, sigmoid activation of the WT channel (A), and the faster, exponential turn‐on of the monomer (C terminus truncated, HV1ΔC) both during pulses to +50 mV at 23°C at pHo 7.5, pHi 7.5. [Adapted from reference . Originally published in The Journal of Physiology.] (C) The time course of movement of a fluorescent probe attached to the S4 domain of the Ciona proton channel is exponential (red). This time course raised to the second power (green) matches the proton current recorded at the same time (black). [Adapted, with permission, from reference . Adapted, with permission, from Macmillan Publishers Ltd: Nature Structural & Molecular Biology 17: 51‐56, 2010.]

Figure 5. Figure 5.

Possible dimer interfaces, with the transmembrane domains color coded as: S1 red, S2 yellow, S3 green, and S4 blue. The dimer in A was proposed on the basis of cysteine cross‐linking studies ; the dimer in B was proposed to explain Zn2+ binding studies . External His residues that bind Zn2+ are shown in aqua (cf. Figure . [Adapted, with permission, from reference . Originally published in Channels (Austin) 4: 260‐265, 2010.]

Figure 6. Figure 6.

Hydrogen‐bonded chain (HBC) conduction. In this schematic example, hydroxyl groups (e.g., from Ser residues) form a HBC that spans the membrane. (A) Proton conduction occurs when a proton enters the chain from the left to form a positive ion, which then moves to the right by hopping of successive protons to effect a reversal of the direction of the hydrogen bonds between each pair of oxygen atoms. Proton conduction would also occur by loss of a proton on the right followed by movement of a negative ion (or fault) to the left. (B) To complete the process, reorientation of each hydrogen bond in the chain must occur, so that another proton can enter from the same side. [Redrawn, with permission, from reference .]

Figure 7. Figure 7.

Determination of the single channel conductance from proton current fluctuations that reflect the stochastic opening and closing of proton channels. “A” shows families of proton currents in an excised, inside‐out patch from a human eosinophil at three pHi values. At subthreshold voltages, the current is quiet, but just above Vthreshold, proton channels begin to open, and the current becomes distinctly noisy. It is noteworthy that (at low pHi) the noise first increases with depolarization, but then decreases for large depolarizations. “B” shows gHV relationships from this patch. The variance of the current fluctuation, measured at quasi‐steady‐state, is plotted in “C.” The variance increases more than 100‐fold at voltages where the proton conductance is active, and is maximal near the midpoint of the gHV relationship at each pHi (indicated as V1/2). “D” shows that the expected variance given the simplest possible two‐state model of gating (closed ↔ open) coincides with the observed voltage dependence. The nonmonotonic increase in variance with depolarization is consistent with the maximum Popen limiting to approximately 0.95 at pHi 5.5.

Adapted, with permission, from reference © Cherny et al., 2003. Originally published in The Journal of General Physiology.
Figure 8. Figure 8.

(A‐D) Effects of pHi on voltage‐gated proton currents in an inside‐out membrane patch from a rat alveolar epithelial cell. The pipette pH (i.e., pHo) was 7.5. “A” shows proton currents in a cell‐attached patch that increase gradually with time during each pulse because the single channel proton currents are too small to resolve. Superimposed are large single channel currents most likely due to Kv1.3 delayed rectifier channels that dominate macroscopic currents in these cells . After this patch was excised into K+‐free solutions, the same population of proton channels generated the currents shown in “B‐D” at the indicated pHi. As pHi was decreased, the currents became larger and activated much more rapidly (note the changing calibrations). The graph in E shows average activation time constants (τact) obtained by single exponential fits in many patches. Changing pHo shifts the kinetics along the voltage axis with little change in the range of τact values. In contrast, changes in pHi profoundly affect τact, with an approximately 5‐fold slowing per unit increase in pHi.

Adapted, with permission, from reference . Originally published in The Journal of Physiology 489:299‐307, 1995.
Figure 9. Figure 9.

(A) Families of proton currents at different pHo//pHi in three rat alveolar epithelial cells (one in each row). The most obvious effect of pH is to vary the voltage range in which proton channels open. (B) Average current‐voltage relationships at the indicated ΔpH, where ΔpH = pHo − pHi, illustrate that the position of the gHV relationship is completely determined by ΔpH. The “Rule of Forty” (Eqs. ) expresses the 40‐mV shift in the position of the gHV relationship that occurs when ΔpH changes by one unit, regardless of whether pHo or pHi is changed.

Adapted, with permission, from reference © Cherny et al., 1995. Originally published in The Journal of General Physiology 105:861‐896.
Figure 10. Figure 10.

Regulation of the position of the gHV relationship by ΔpH occurs in all known voltage‐gated proton channels. In most species, this regulation results in Vthreshold always being positive to the reversal potential, Vrev, thus ensuring that when proton channels open, acid will be extruded. The blue line shows the result of linear regression on data reported in 15 cell types that are listed in reference ; the dashed red line shows equality between Vthreshold and Vrev for comparison. In the recently identified kHv1 channel in the dinoflagellate, Karlodiniun veneficum, Vthreshold is shifted by −60 mV relative to all other species (green data points and line), with the result that depolarization above Vthreshold will produce inward H+ current in kHV1 at all ΔpH .

Figure 11. Figure 11.

Proton channel gating is strongly temperature dependent. (A, B) In a human neutrophil at pHo 7.0, pHi 5.5 at the indicated temperatures, a depolarizing prepulse activated the gH, then the voltage was stepped to test voltages, illustrated in 20‐mV increments. Note the change in time base. The “tail current” (deactivation or closing) time constant, τtail, was obtained by fitting a single decaying exponential to each current. The Q10 was identical at all voltages (C) and was 8.5 in this cell, corresponding to an activation energy of approximately 38 kcal/mol.

Adapted, with permission, from reference © DeCoursey & Cherny, 1998. Originally published in The Journal of General Physiology.
Figure 12. Figure 12.

Modulation of Zn2+ effects on proton currents by pHo reveals strong competition between Zn2+ and H+ for external binding sites. Identical families of pulses were applied in each row at the indicated pHo and Zn2+ concentrations. Zn2+ slows activation of the proton current at a given voltage and shifts the gHV relationship positively.

Adapted, with permission, from reference © Cherny & DeCoursey, 1999. Originally published in The Journal of General Physiology.
Figure 13. Figure 13.

The pHo dependence of the slowing of proton current activation can be explained if Zn2+ binds to a site consisting of three groups with pKa 6.3, with affinity 316 nmol/L, and cooperativity factor a = 0.03 (see text). All curves were drawn with these values and no other adjustable parameters. Adequate fits were also obtained by assuming two titratable groups, but not with only one. At high pHo competition with protons disappears and limits to simple metal binding. See text for further details.

Adapted, with permission, from reference © Cherny & DeCoursey, 1999. Originally published in The Journal of General Physiology.
Figure 14. Figure 14.

Effects of Zn2+ on Vthreshold (A) and on the slowing of proton current activation (B) in constructs with several His mutations. Dimeric proton channels are illustrated with diagrams in which solid symbols indicate His and open symbols indicate Ala substituted for His. Three tandem dimers are shown with their C‐ and N‐termini linked to constrain the His positions in the dimer. Vthreshold shifts were estimated from gHV relationships plotted semilogarithmically. Statistical comparisons are to WT channel parameters (P < 0.05, *P < 0.01).

Adapted, with permission, from reference . Originally published in The Journal of Physiology 588:1435‐1449, 2010.
Figure 15. Figure 15.

Proposed mechanism by which proton flux through voltage‐gated proton channels triggers light flashes in dinoflagellates. Mechanical stimulation elicits an action potential conducted along the tonoplast, the membrane separating the central vacuole and a thin layer of cytoplasm (gray). When the action potential invades the scintillons (grape‐like structures formed by evagination of tonoplast), proton flux from the vacuole at low pH into the scintillon activates luciferase, triggering the flash.

Adapted, with permission, from reference . Originally published in Hastings JW. Bioluminescence. In: Cell Physiology Sourcebook: A Molecular Approach (3rd ed.), Sperelakis N, editor. San Diego: Academic Press, 2001, p. 1115‐1131.
Figure 16. Figure 16.

Rapidly activating proton currents in a Lymnaea snail neuron, 120 μm in diameter. Currents during pulses to the voltages shown at pHo 7.4, pHi 5.9 at room temperature.

Originally published in The Journal of Physiology

351:199‐216, 1984.]

Adapted, with permission, from reference .
Figure 17. Figure 17.

Schematic representation of the role of the proton channel (HVCN1) in the context of B cell receptor (BCR) stimulation. Antigen binding to the BCR results in phosphorylation of immunoreceptor tyrosine activation motif (ITAMs) in the Ig‐α/β heterodimer by LYN, creating docking sites for Syk. This serves to amplify BCR signaling by further recruitment and activation of Syk, which leads to PI3K activation, activation of Akt and increased glucose uptake and metabolism. Amplification of signaling is negatively regulated by CD22, which is also phosphorylated by LYN, providing a docking site for protein tyrosine phosphatase SHP‐1. In resting cells, SHP‐1 inhibits B cell activation by dephosphorylating Syk, thus counterbalancing ITAM‐Syk mediated signal amplification. BCR stimulation results in reactive oxygen species (ROS) generated by NADPH oxidase. The O2.− that is produced combines with protons to form H2O2 and O2, which freely diffuse through the membrane. ROS generate a localized oxidizing environment causing inhibition of SHP‐1, which results in amplification of BCR signal. HVCN1 sustains NADPH oxidase activity. In the absence of HVCN1, the oxidizing environment cannot be maintained and consequently SHP‐1 remains active, reducing BCR‐signal strength.

Adapted, with permission, from reference . Originally published in Nature Immunology 11: 265‐272, 2010.]
Figure 18. Figure 18.

Proton husbandry during the phagocyte respiratory burst. Upon stimulation, the components of the NADPH oxidase complex assemble at the membrane and begin to relay electrons from NADPH across the membrane to reduce O2 to superoxide anion, O2.−. Because of the massive increase in O2 consumption, this process is called the “respiratory burst” despite the fact that most of the O2 is consumed to make reactive oxygen species (ROS) and it is not affected by mitochondrial inhibitors . Protons left behind in the cytoplasm exit mainly through voltage‐gated proton channels , although other transporters also play important roles . Inside the phagosome, protons are consumed during the spontaneous dismutation of O2.− to H2O2 as well as during HOCl generation by myeloperoxidase (MPO) . [Adapted, with permission, from reference . Originally published in Physiology 25: 27‐40, 2010.]

Figure 19. Figure 19.

The pHi in four individual human neutrophils during phagocytosis of opsonized zymosan (OPZ) is plotted, with pseudocolor confocal images of each cell at corresponding times. The cells were loaded with the pH sensing dye, SNARF‐1. In control cells, pHi drops rapidly when OPZ is ingested and often recovers rapidly (A), but in some cells does not (B). Recovery is prevented by 20 μmol/L dimethylamiloride, which inhibits the Na+/H+ antiporter (C) or 100 μmol/L Zn2+, which inhibits proton channels (D). Among the inhibitors tested, only Zn2+ increased the rate of acidification, indicating that proton channels contribute significantly at early times. [Adapted, with permission, from reference . Originally published in Proceedings of the National Academy of Sciences, USA 106: 18022‐18027, 2009.]

Figure 20. Figure 20.

The enhanced gating mode of proton channels in human eosinophils. (A) The onset of enhanced gating in a human eosinophil stimulated with 30 nmol/L PMA in perforated‐patch configuration at symmetrical pH 7.0. Test pulses to +60 mV applied at 30‐s intervals are superimposed, before and up to 6 min after addition of PMA, illustrating the increasing current, faster activation, and slower tail current decay. The downward shift of the baseline current at −60 mV reflects electron current generated by NADPH oxidase activity. (B) The time course of proton current enhancement (top) after stimulation with PMA (arrow) and subsequent inhibition of PKC by 3 μmol/L GF109203X (GFX) (arrow) in a different human eosinophil. Repeated test pulses to +60 mV were applied, and only the peak current is evident at this time scale. The inward electron current at −60 mV in this cell can be seen as a downward deflection in the holding current, which is amplified in the lower panel (the pulses eliciting proton current are blanked). “C” shows individual currents during test pulses applied at times indicated in “B” by lower‐case letters. The inward electron current at the holding potential is clearly evident. [Adapted, with permission, from reference . (A) Originally published in The Journal of Physiology 535: 767‐781, 2001 and from reference (B, C) Originally published in The Journal of Physiology 579: 327‐344, 2007.]

Figure 21. Figure 21.

Confocal images of four human basophils taken at 30‐s intervals (left to right, then top to bottom) during their response to anti‐IgE stimulation. The pseudocolors indicate pHi detected with SNARF‐1 in confocal slices approximately 0.2 μm thick, with alkaline to acidic shown as blue to green to red to yellow. Voltage‐gated proton channels are active during the response and limit the extent of acidification. (Image provided by Deri Morgan with permission.)



Figure 1.

Voltage‐gated proton channels trigger the bioluminescent light flash in dinoflagellates. The proton concentration is high in the flotation vacuole (below the membrane in the diagram). An action potential depolarizes the membrane, opening proton channels, allowing protons to flow down their electrochemical gradient into the interior of the scintillon (upper compartment). The sudden drop in pH in the scintillon triggers the flash by two concerted mechanisms. Upon protonation, the light‐emitting pigment, luciferin (LH2) is released from luciferin‐binding protein (LBP) making it available as a substrate for luciferase, which is itself activated by acidification. [Adapted, with permission, from reference . Originally published in Bioluminescence in Action, edited by P. Herring, Academic Press, London. pp. 129‐170, 1978. Copyright Elsevier.]



Figure 2.

Membrane topology of voltage‐gated K+ channels (left), voltage‐gated proton channels (center), and voltage‐sensitive phosphatases (right). The K+ channel (lower panel) is a tetramer of the six transmembrane domain monomer shown in the top; the proton channel is a homodimer of the four transmembrane domain monomer in the top panel, and the phosphatase is a monomer. The assembled K+ channel has a single conduction pathway, but the proton channel has two, one in each protomer. The voltage‐sensing phosphatase (VSP) senses voltage, but does not conduct. The proton channel cartoon illustrates schematically that the dimer is held together by C‐terminal coiled‐coil interactions, and that the channel can be phosphorylated at Thr29 in the intracellular N terminus to produce the enhanced gating mode (cf. Figure 20). [Figure adapted, with permission, from reference . Originally published in Physiology 25:27‐40, 2010.]



Figure 3.

A phylogenetic analysis showing evolutionary relationships among 37 putative HV1 voltage‐sensing domain (VSD) sequences. This maximum likelihood phylogenetic tree with 100 boostraps was constructed from a multiple sequence alignment of the VSD portion of 37 HV1s; N‐ and C‐termini were truncated. Branch lengths are displayed to scale, and are proportional to the evolutionary distance between sequences. Bootstrap values greater than 60 are shown. [Figure adapted, with permission, from reference . Originally published in Proc. Natl. Acad. Sci. U S A. 108:18162‐18168, 2011.].



Figure 4.

Comparison of gating kinetics of the human proton channel dimer (A) and monomer (B), expressed in HEK‐293 cells. Note the slower, sigmoid activation of the WT channel (A), and the faster, exponential turn‐on of the monomer (C terminus truncated, HV1ΔC) both during pulses to +50 mV at 23°C at pHo 7.5, pHi 7.5. [Adapted from reference . Originally published in The Journal of Physiology.] (C) The time course of movement of a fluorescent probe attached to the S4 domain of the Ciona proton channel is exponential (red). This time course raised to the second power (green) matches the proton current recorded at the same time (black). [Adapted, with permission, from reference . Adapted, with permission, from Macmillan Publishers Ltd: Nature Structural & Molecular Biology 17: 51‐56, 2010.]



Figure 5.

Possible dimer interfaces, with the transmembrane domains color coded as: S1 red, S2 yellow, S3 green, and S4 blue. The dimer in A was proposed on the basis of cysteine cross‐linking studies ; the dimer in B was proposed to explain Zn2+ binding studies . External His residues that bind Zn2+ are shown in aqua (cf. Figure . [Adapted, with permission, from reference . Originally published in Channels (Austin) 4: 260‐265, 2010.]



Figure 6.

Hydrogen‐bonded chain (HBC) conduction. In this schematic example, hydroxyl groups (e.g., from Ser residues) form a HBC that spans the membrane. (A) Proton conduction occurs when a proton enters the chain from the left to form a positive ion, which then moves to the right by hopping of successive protons to effect a reversal of the direction of the hydrogen bonds between each pair of oxygen atoms. Proton conduction would also occur by loss of a proton on the right followed by movement of a negative ion (or fault) to the left. (B) To complete the process, reorientation of each hydrogen bond in the chain must occur, so that another proton can enter from the same side. [Redrawn, with permission, from reference .]



Figure 7.

Determination of the single channel conductance from proton current fluctuations that reflect the stochastic opening and closing of proton channels. “A” shows families of proton currents in an excised, inside‐out patch from a human eosinophil at three pHi values. At subthreshold voltages, the current is quiet, but just above Vthreshold, proton channels begin to open, and the current becomes distinctly noisy. It is noteworthy that (at low pHi) the noise first increases with depolarization, but then decreases for large depolarizations. “B” shows gHV relationships from this patch. The variance of the current fluctuation, measured at quasi‐steady‐state, is plotted in “C.” The variance increases more than 100‐fold at voltages where the proton conductance is active, and is maximal near the midpoint of the gHV relationship at each pHi (indicated as V1/2). “D” shows that the expected variance given the simplest possible two‐state model of gating (closed ↔ open) coincides with the observed voltage dependence. The nonmonotonic increase in variance with depolarization is consistent with the maximum Popen limiting to approximately 0.95 at pHi 5.5.

Adapted, with permission, from reference © Cherny et al., 2003. Originally published in The Journal of General Physiology.


Figure 8.

(A‐D) Effects of pHi on voltage‐gated proton currents in an inside‐out membrane patch from a rat alveolar epithelial cell. The pipette pH (i.e., pHo) was 7.5. “A” shows proton currents in a cell‐attached patch that increase gradually with time during each pulse because the single channel proton currents are too small to resolve. Superimposed are large single channel currents most likely due to Kv1.3 delayed rectifier channels that dominate macroscopic currents in these cells . After this patch was excised into K+‐free solutions, the same population of proton channels generated the currents shown in “B‐D” at the indicated pHi. As pHi was decreased, the currents became larger and activated much more rapidly (note the changing calibrations). The graph in E shows average activation time constants (τact) obtained by single exponential fits in many patches. Changing pHo shifts the kinetics along the voltage axis with little change in the range of τact values. In contrast, changes in pHi profoundly affect τact, with an approximately 5‐fold slowing per unit increase in pHi.

Adapted, with permission, from reference . Originally published in The Journal of Physiology 489:299‐307, 1995.


Figure 9.

(A) Families of proton currents at different pHo//pHi in three rat alveolar epithelial cells (one in each row). The most obvious effect of pH is to vary the voltage range in which proton channels open. (B) Average current‐voltage relationships at the indicated ΔpH, where ΔpH = pHo − pHi, illustrate that the position of the gHV relationship is completely determined by ΔpH. The “Rule of Forty” (Eqs. ) expresses the 40‐mV shift in the position of the gHV relationship that occurs when ΔpH changes by one unit, regardless of whether pHo or pHi is changed.

Adapted, with permission, from reference © Cherny et al., 1995. Originally published in The Journal of General Physiology 105:861‐896.


Figure 10.

Regulation of the position of the gHV relationship by ΔpH occurs in all known voltage‐gated proton channels. In most species, this regulation results in Vthreshold always being positive to the reversal potential, Vrev, thus ensuring that when proton channels open, acid will be extruded. The blue line shows the result of linear regression on data reported in 15 cell types that are listed in reference ; the dashed red line shows equality between Vthreshold and Vrev for comparison. In the recently identified kHv1 channel in the dinoflagellate, Karlodiniun veneficum, Vthreshold is shifted by −60 mV relative to all other species (green data points and line), with the result that depolarization above Vthreshold will produce inward H+ current in kHV1 at all ΔpH .



Figure 11.

Proton channel gating is strongly temperature dependent. (A, B) In a human neutrophil at pHo 7.0, pHi 5.5 at the indicated temperatures, a depolarizing prepulse activated the gH, then the voltage was stepped to test voltages, illustrated in 20‐mV increments. Note the change in time base. The “tail current” (deactivation or closing) time constant, τtail, was obtained by fitting a single decaying exponential to each current. The Q10 was identical at all voltages (C) and was 8.5 in this cell, corresponding to an activation energy of approximately 38 kcal/mol.

Adapted, with permission, from reference © DeCoursey & Cherny, 1998. Originally published in The Journal of General Physiology.


Figure 12.

Modulation of Zn2+ effects on proton currents by pHo reveals strong competition between Zn2+ and H+ for external binding sites. Identical families of pulses were applied in each row at the indicated pHo and Zn2+ concentrations. Zn2+ slows activation of the proton current at a given voltage and shifts the gHV relationship positively.

Adapted, with permission, from reference © Cherny & DeCoursey, 1999. Originally published in The Journal of General Physiology.


Figure 13.

The pHo dependence of the slowing of proton current activation can be explained if Zn2+ binds to a site consisting of three groups with pKa 6.3, with affinity 316 nmol/L, and cooperativity factor a = 0.03 (see text). All curves were drawn with these values and no other adjustable parameters. Adequate fits were also obtained by assuming two titratable groups, but not with only one. At high pHo competition with protons disappears and limits to simple metal binding. See text for further details.

Adapted, with permission, from reference © Cherny & DeCoursey, 1999. Originally published in The Journal of General Physiology.


Figure 14.

Effects of Zn2+ on Vthreshold (A) and on the slowing of proton current activation (B) in constructs with several His mutations. Dimeric proton channels are illustrated with diagrams in which solid symbols indicate His and open symbols indicate Ala substituted for His. Three tandem dimers are shown with their C‐ and N‐termini linked to constrain the His positions in the dimer. Vthreshold shifts were estimated from gHV relationships plotted semilogarithmically. Statistical comparisons are to WT channel parameters (P < 0.05, *P < 0.01).

Adapted, with permission, from reference . Originally published in The Journal of Physiology 588:1435‐1449, 2010.


Figure 15.

Proposed mechanism by which proton flux through voltage‐gated proton channels triggers light flashes in dinoflagellates. Mechanical stimulation elicits an action potential conducted along the tonoplast, the membrane separating the central vacuole and a thin layer of cytoplasm (gray). When the action potential invades the scintillons (grape‐like structures formed by evagination of tonoplast), proton flux from the vacuole at low pH into the scintillon activates luciferase, triggering the flash.

Adapted, with permission, from reference . Originally published in Hastings JW. Bioluminescence. In: Cell Physiology Sourcebook: A Molecular Approach (3rd ed.), Sperelakis N, editor. San Diego: Academic Press, 2001, p. 1115‐1131.


Figure 16.

Rapidly activating proton currents in a Lymnaea snail neuron, 120 μm in diameter. Currents during pulses to the voltages shown at pHo 7.4, pHi 5.9 at room temperature.

Originally published in The Journal of Physiology

351:199‐216, 1984.]

Adapted, with permission, from reference .


Figure 17.

Schematic representation of the role of the proton channel (HVCN1) in the context of B cell receptor (BCR) stimulation. Antigen binding to the BCR results in phosphorylation of immunoreceptor tyrosine activation motif (ITAMs) in the Ig‐α/β heterodimer by LYN, creating docking sites for Syk. This serves to amplify BCR signaling by further recruitment and activation of Syk, which leads to PI3K activation, activation of Akt and increased glucose uptake and metabolism. Amplification of signaling is negatively regulated by CD22, which is also phosphorylated by LYN, providing a docking site for protein tyrosine phosphatase SHP‐1. In resting cells, SHP‐1 inhibits B cell activation by dephosphorylating Syk, thus counterbalancing ITAM‐Syk mediated signal amplification. BCR stimulation results in reactive oxygen species (ROS) generated by NADPH oxidase. The O2.− that is produced combines with protons to form H2O2 and O2, which freely diffuse through the membrane. ROS generate a localized oxidizing environment causing inhibition of SHP‐1, which results in amplification of BCR signal. HVCN1 sustains NADPH oxidase activity. In the absence of HVCN1, the oxidizing environment cannot be maintained and consequently SHP‐1 remains active, reducing BCR‐signal strength.

Adapted, with permission, from reference . Originally published in Nature Immunology 11: 265‐272, 2010.]


Figure 18.

Proton husbandry during the phagocyte respiratory burst. Upon stimulation, the components of the NADPH oxidase complex assemble at the membrane and begin to relay electrons from NADPH across the membrane to reduce O2 to superoxide anion, O2.−. Because of the massive increase in O2 consumption, this process is called the “respiratory burst” despite the fact that most of the O2 is consumed to make reactive oxygen species (ROS) and it is not affected by mitochondrial inhibitors . Protons left behind in the cytoplasm exit mainly through voltage‐gated proton channels , although other transporters also play important roles . Inside the phagosome, protons are consumed during the spontaneous dismutation of O2.− to H2O2 as well as during HOCl generation by myeloperoxidase (MPO) . [Adapted, with permission, from reference . Originally published in Physiology 25: 27‐40, 2010.]



Figure 19.

The pHi in four individual human neutrophils during phagocytosis of opsonized zymosan (OPZ) is plotted, with pseudocolor confocal images of each cell at corresponding times. The cells were loaded with the pH sensing dye, SNARF‐1. In control cells, pHi drops rapidly when OPZ is ingested and often recovers rapidly (A), but in some cells does not (B). Recovery is prevented by 20 μmol/L dimethylamiloride, which inhibits the Na+/H+ antiporter (C) or 100 μmol/L Zn2+, which inhibits proton channels (D). Among the inhibitors tested, only Zn2+ increased the rate of acidification, indicating that proton channels contribute significantly at early times. [Adapted, with permission, from reference . Originally published in Proceedings of the National Academy of Sciences, USA 106: 18022‐18027, 2009.]



Figure 20.

The enhanced gating mode of proton channels in human eosinophils. (A) The onset of enhanced gating in a human eosinophil stimulated with 30 nmol/L PMA in perforated‐patch configuration at symmetrical pH 7.0. Test pulses to +60 mV applied at 30‐s intervals are superimposed, before and up to 6 min after addition of PMA, illustrating the increasing current, faster activation, and slower tail current decay. The downward shift of the baseline current at −60 mV reflects electron current generated by NADPH oxidase activity. (B) The time course of proton current enhancement (top) after stimulation with PMA (arrow) and subsequent inhibition of PKC by 3 μmol/L GF109203X (GFX) (arrow) in a different human eosinophil. Repeated test pulses to +60 mV were applied, and only the peak current is evident at this time scale. The inward electron current at −60 mV in this cell can be seen as a downward deflection in the holding current, which is amplified in the lower panel (the pulses eliciting proton current are blanked). “C” shows individual currents during test pulses applied at times indicated in “B” by lower‐case letters. The inward electron current at the holding potential is clearly evident. [Adapted, with permission, from reference . (A) Originally published in The Journal of Physiology 535: 767‐781, 2001 and from reference (B, C) Originally published in The Journal of Physiology 579: 327‐344, 2007.]



Figure 21.

Confocal images of four human basophils taken at 30‐s intervals (left to right, then top to bottom) during their response to anti‐IgE stimulation. The pseudocolors indicate pHi detected with SNARF‐1 in confocal slices approximately 0.2 μm thick, with alkaline to acidic shown as blue to green to red to yellow. Voltage‐gated proton channels are active during the response and limit the extent of acidification. (Image provided by Deri Morgan with permission.)

 1. Accardi A, Miller C. Secondary active transport mediated by a prokaryotic homologue of ClC Cl− channels. Nature 427: 803‐807, 2004.
 2. Acharya R, Carnevale V, Fiorin G, Levine BG, Polishchuk AL, Balannik V, Samish I, Lamb RA, Pinto LH, DeGrado WF, Klein ML. Structure and mechanism of proton transport through the transmembrane tetrameric M2 protein bundle of the influenza A virus. Proc Natl Acad Sci U S A 107: 15075‐15080, 2010.
 3. Agmon N. The Grotthuss mechanism. Chem Phys Lett 244: 456‐462, 1995.
 4. Agre P, King LS, Yasui M, Guggino WB, Ottersen OP, Fujiyoshi Y, Engel A, Nielsen S. Aquaporin water channels–from atomic structure to clinical medicine. J Physiol 542: 3‐16, 2002.
 5. Ahmed Z, Connor JA. Intracellular pH changes induced by calcium influx during electrical activity in molluscan neurons. J Gen Physiol 75: 403‐426, 1980.
 6. Akeson M, Deamer DW. Proton conductance by the gramicidin water wire. Model for proton conductance in the F1F0 ATPases? Biophys J 60: 101‐109, 1991.
 7. Alabi AA, Bahamonde MI, Jung HJ, Kim JI, Swartz KJ. Portability of paddle motif function and pharmacology in voltage sensors. Nature 450: 370‐375, 2007.
 8. Babcock DF, Pfeiffer DR. Independent elevation of cytosolic [Ca2+] and pH of mammalian sperm by voltage‐dependent and pH‐sensitive mechanisms. J Biol Chem 262: 15041‐15047, 1987.
 9. Babcock DF, Rufo GA, Jr, Lardy HA. Potassium‐dependent increases in cytosolic pH stimulate metabolism and motility of mammalian sperm. Proc Natl Acad Sci U S A 80: 1327‐1331, 1983.
 10. Babior BM, Kipnes RS, Curnutte JT. Biological defense mechanisms. The production by leukocytes of superoxide, a potential bactericidal agent. J Clin Invest 52: 741‐744, 1973.
 11. Bachvaroff TR, Place AR. From stop to start: Tandem gene arrangement, copy number and trans‐splicing sites in the dinoflagellate Amphidinium carterae. PLoS One 3: e2929, 2008.
 12. Baldridge CW, Gerard RW. The extra respiration of phagocytosis. Am J Physiol 103: 235‐236, 1932.
 13. Ballantine D, Abbott BC. Toxic marine flagellates; their occurrence and physiological effects on animals. J Gen Microbiol 16: 274‐281, 1957.
 14. Bánfi B, Maturana A, Jaconi S, Arnaudeau S, Laforge T, Sinha B, Ligeti E, Demaurex N, Krause KH. A mammalian H+ channel generated through alternative splicing of the NADPH oxidase homolog NOH‐1. Science 287: 138‐142, 2000.
 15. Bánfi B, Molnár G, Maturana A, Steger K, Hegedûs B, Demaurex N, Krause KH. A Ca2+‐activated NADPH oxidase in testis, spleen, and lymph nodes. J Biol Chem 276: 37594‐37601, 2001.
 16. Bánfi B, Schrenzel J, Nüsse O, Lew DP, Ligeti E, Krause KH, Demaurex N. A novel H+ conductance in eosinophils: Unique characteristics and absence in chronic granulomatous disease. J Exp Med 190: 183‐194, 1999.
 17. Bankers‐Fulbright JL, Gleich GJ, Kephart GM, Kita H, O'Grady SM. Regulation of eosinophil membrane depolarization during NADPH oxidase activation. J Cell Sci 116: 3221‐3226, 2003.
 18. Bankers‐Fulbright JL, Kita H, Gleich GJ, O'Grady SM. Regulation of human eosinophil NADPH oxidase activity: a central role for PKCδ. J Cell Physiol 189: 306‐315, 2001.
 19. Barish ME, Baud C. A voltage‐gated hydrogen ion current in the oocyte membrane of the axolotl, Ambystoma. J Physiol 352: 243‐263, 1984.
 20. Baud C, Barish ME. Changes in membrane hydrogen and sodium conductances during progesterone‐induced maturation of Ambystoma oocytes. Dev Biol 105: 423‐434, 1984.
 21. Beaufort L, Probert I, de Garidel‐Thoron T, Bendif EM, Ruiz‐Pino D, Metzl N, Goyet C, Buchet N, Coupel P, Grelaud M, Rost B, Rickaby RE, de Vargas C. Sensitivity of coccolithophores to carbonate chemistry and ocean acidification. Nature 476: 80‐83, 2011.
 22. Bergholtz T, Daubjerg N, Moestrup Ø, Fernández‐Tejedor M. On the identity of Karlodinium veneficum and description of Karlodinium armiger sp. nov. (Dinophyceae), based on light and electron microscopy, nuclear‐encoded LSU rDNA, and pigment composition. J Phycol 42: 170‐193, 2005.
 23. Bernal JD, Fowler RH. A theory of water and ionic solution, with particular reference to hydrogen and hydroxyl ions. J Chem Phys 1: 515‐548, 1933.
 24. Bernheim L, Krause RM, Baroffio A, Hamann M, Kaelin A, Bader CR. A voltage‐dependent proton current in cultured human skeletal muscle myotubes. J Physiol 470: 313‐333, 1993.
 25. Bode VC, Hastings JW. The purification and properties of the bioluminescent system in Gonyaulax polyedra. Arch Biochem Biophys 103: 488‐499, 1963.
 26. Borregaard N, Schwartz JH, Tauber AI. Proton secretion by stimulated neutrophils. Significance of hexose monophosphate shunt activity as source of electrons and protons for the respiratory burst. J Clin Invest 74: 455‐459, 1984.
 27. Brändén G, Gennis RB, Brzezinski P. Transmembrane proton translocation by cytochrome c oxidase. Biochim Biophys Acta 1757: 1052‐1063, 2006.
 28. Burykin A, Warshel A. What really prevents proton transport through aquaporin? Charge self‐energy versus proton wire proposals. Biophys J 85: 3696‐3706, 2003.
 29. Byerly L, Meech R, Moody W, Jr Rapidly activating hydrogen ion currents in perfused neurones of the snail, Lymnaea stagnalis. J Physiol 351: 199‐216, 1984.
 30. Byerly L, Suen Y. Characterization of proton currents in neurones of the snail, Lymnaea stagnalis. J Physiol 413: 75‐89, 1989.
 31. Cameron AR, Nelson J, Forman HJ. Depolarization and increased conductance precede superoxide release by concanavalin A‐stimulated rat alveolar macrophages. Proc Natl Acad Sci U S A 80: 3726‐3728, 1983.
 32. Capasso M, Bhamrah MK, Henley T, Boyd RS, Langlais C, Cain K, Dinsdale D, Pulford K, Khan M, Musset B, Cherny VV, Morgan D, Gascoyne RD, Vigorito E, DeCoursey TE, MacLennan IC, Dyer MJ. HVCN1 modulates BCR signal strength via regulation of BCR‐dependent generation of reactive oxygen species. Nat Immunol 11: 265‐272, 2010.
 33. Chakrabarti N, Tajkhorshid E, Roux B, Pomès R. Molecular basis of proton blockage in aquaporins. Structure 12: 65‐74, 2004.
 34. Chang JJ. Electrophysiological studies of a non‐luminescent form of the dinoflagellate Noctiluca miliaris. J Cell Comp Physiol 56: 33‐42, 1960.
 35. Cheng YM, Kelly T, Church J. Potential contribution of a voltage‐activated proton conductance to acid extrusion from rat hippocampal neurons. Neuroscience 151: 1084‐1098, 2008.
 36. Cherny VV, DeCoursey TE. pH‐dependent inhibition of voltage‐gated H+ currents in rat alveolar epithelial cells by Zn2+ and other divalent cations. J Gen Physiol 114: 819‐838, 1999.
 37. Cherny VV, Henderson LM, Xu W, Thomas LL, DeCoursey TE. Activation of NADPH oxidase‐related proton and electron currents in human eosinophils by arachidonic acid. J Physiol 535: 783‐794, 2001.
 38. Cherny VV, Markin VS, DeCoursey TE. The voltage‐activated hydrogen ion conductance in rat alveolar epithelial cells is determined by the pH gradient. J Gen Physiol 105: 861‐896, 1995.
 39. Cherny VV, Murphy R, Sokolov V, Levis RA, DeCoursey TE. Properties of single voltage‐gated proton channels in human eosinophils estimated by noise analysis and by direct measurement. J Gen Physiol 121: 615‐628, 2003.
 40. Cherny VV, Thomas LL, DeCoursey TE. Voltage‐gated proton currents in human basophils. Biol Membrany 18: 458‐465, 2001.
 41. Chernyshev A, Cukierman S. Thermodynamic view of activation energies of proton transfer in various gramicidin A channels. Biophys J 82: 182‐192, 2002.
 42. Chernyshev A, Pomès R, Cukierman S. Kinetic isotope effects of proton transfer in aqueous and methanol containing solutions, and in gramicidin A channels. Biophys Chem 103: 179‐190, 2003.
 43. Chizhmakov IV, Geraghty FM, Ogden DC, Hayhurst A, Antoniou M, Hay AJ. Selective proton permeability and pH regulation of the influenza virus M2 channel expressed in mouse erythroleukaemia cells. J Physiol 494: 329‐336, 1996.
 44. Cho DY, Hajighasemi M, Hwang PH, Illek B, Fischer H. Proton secretion in freshly excised sinonasal mucosa from asthma and sinusitis patients. Am J Rhinol Allergy 23: e10‐e13, 2009.
 45. Cohen HJ, Newburger PE, Chovaniec ME, Whitin JC, Simons ER. Opsonized zymosan‐stimulated granulocytes‐activation and activity of the superoxide‐generating system and membrane potential changes. Blood 58: 975‐982, 1981.
 46. Cole KS, Moore JW. Potassium ion current in the squid giant axon: Dynamic characteristic. Biophys J 1: 1‐14, 1960.
 47. Conway BE, Bockris JOM, Linton H. Proton conductance and the existence of the H3O. ion. J Chem Phys 24: 834‐850, 1956.
 48. Cukierman S. Flying protons in linked gramicidin A channels. Israel J Chem 39: 419‐426, 1999.
 49. Danneel H. Notiz über Ionengeschwindigkeiten. Z Elktrochem Angew P 11: 249‐252, 1905.
 50. de Boer M, Roos D. Metabolic comparison between basophils and other leukocytes from human blood. J Immunol 136: 3447‐3454, 1986.
 51. de Groot BL, Frigato T, Helms V, Grubmüller H. The mechanism of proton exclusion in the aquaporin‐1 water channel. J Mol Biol 333: 279‐293, 2003.
 52. de Grotthuss CJ. Memoir on the decomposition of water and of the bodies that it holds in solution by means of galvanic electricity. Biochim Biophys Acta 1757: 871‐875, 2006.
 53. de Grotthuss CJT. Sur la décomposition de l'eau et des corps qu'elle tient en dissolution à l'aide de l’électricité galvanique. Annales de Chimie LVIII: 54‐74, 1806.
 54. DeCoursey TE. Hydrogen ion currents in rat alveolar epithelial cells. Biophys J 60: 1243‐1253, 1991.
 55. DeCoursey TE. Hypothesis: Do voltage‐gated H+ channels in alveolar epithelial cells contribute to CO2 elimination by the lung? Am J Physiol Cell Physiol 278: C1‐C10, 2000.
 56. DeCoursey TE. Voltage‐gated proton channels and other proton transfer pathways. Physiol Rev 83: 475‐579, 2003.
 57. DeCoursey TE. Voltage‐gated proton channels: What's next? J Physiol 586: 5305‐5324, 2008.
 58. DeCoursey TE. Voltage‐gated proton channels find their dream job managing the respiratory burst in phagocytes. Physiology (Bethesda) 25: 27‐40, 2010.
 59. DeCoursey TE, Chandy KG, Gupta S, Cahalan MD. Voltage‐gated K+ channels in human T lymphocytes: A role in mitogenesis? Nature 307: 465‐468, 1984.
 60. DeCoursey TE, Cherny VV. Potential, pH, and arachidonate gate hydrogen ion currents in human neutrophils. Biophys J 65: 1590‐1598, 1993.
 61. DeCoursey TE, Cherny VV. Na+‐H+ antiport detected through hydrogen ion currents in rat alveolar epithelial cells and human neutrophils. J Gen Physiol 103: 755‐785, 1994.
 62. DeCoursey TE, Cherny VV. Voltage‐activated hydrogen ion currents. J Membr Biol 141: 203‐223, 1994.
 63. DeCoursey TE, Cherny VV. Voltage‐activated proton currents in membrane patches of rat alveolar epithelial cells. J Physiol 489: 299‐307, 1995.
 64. DeCoursey TE, Cherny VV. Effects of buffer concentration on voltage‐gated H+ currents: Does diffusion limit the conductance? Biophys J 71: 182‐193, 1996.
 65. DeCoursey TE, Cherny VV. Voltage‐activated proton currents in human THP‐1 monocytes. J Membr Biol 152: 131‐140, 1996.
 66. DeCoursey TE, Cherny VV. Deuterium isotope effects on permeation and gating of proton channels in rat alveolar epithelium. J Gen Physiol 109: 415‐434, 1997.
 67. DeCoursey TE, Cherny VV. Temperature dependence of voltage‐gated H+ currents in human neutrophils, rat alveolar epithelial cells, and mammalian phagocytes. J Gen Physiol 112: 503‐522, 1998.
 68. DeCoursey TE, Cherny VV, DeCoursey AG, Xu W, Thomas LL. Interactions between NADPH oxidase‐related proton and electron currents in human eosinophils. J Physiol 535: 767‐781, 2001.
 69. DeCoursey TE, Cherny VV, Morgan D, Katz BZ, Dinauer MC. The gp91phox component of NADPH oxidase is not the voltage‐gated proton channel in phagocytes, but it helps. J Biol Chem 276: 36063‐36066, 2001.
 70. DeCoursey TE, Cherny VV, Zhou W, Thomas LL. Simultaneous activation of NADPH oxidase‐related proton and electron currents in human neutrophils. Proc Natl Acad Sci U S A 97: 6885‐6889, 2000.
 71. DeCoursey TE, Jacobs ER, Silver MR. Potassium currents in rat type II alveolar epithelial cells. J Physiol 395: 487‐505, 1988.
 72. DeCoursey TE, Ligeti E. Regulation and termination of NADPH oxidase activity. Cell Mol Life Sci 62: 2173‐2193, 2005.
 73. DeCoursey TE, Morgan D, Cherny VV. The voltage dependence of NADPH oxidase reveals why phagocytes need proton channels. Nature 422: 531‐534, 2003.
 74. Deeds JR, Terlizzi DE, Adolf JE, Stoecker DK, Place AR. Toxic activity from cultures of Karlodinium micrum (=Gyrodinium galatheanum)(Dinophyceae)‐a dinoflagellate associated with fish mortalities in an estuarine aquaculture facility. Harmful Algae 1: 169‐189, 2002.
 75. Demaurex N, Downey GP, Waddell TK, Grinstein S. Intracellular pH regulation during spreading of human neutrophils. J Cell Biol 133: 1391‐1402, 1996.
 76. Demaurex N, Grinstein S, Jaconi M, Schlegel W, Lew DP, Krause KH. Proton currents in human granulocytes: Regulation by membrane potential and intracellular pH. J Physiol 466: 329‐344, 1993.
 77. Demaurex N, Petheõ GL. Electron and proton transport by NADPH oxidases. Philos Trans R Soc Lond B Biol Sci 360: 2315‐2325, 2005.
 78. DeSa R, Hastings JW. The characterization of scintillons. Bioluminescent particles from the marine dinoflagellate, Gonyaulax polyedra. J Gen Physiol 51: 105‐122, 1968.
 79. Dinauer MC, Nauseef WM, Newburger PEI. Inherited disorders of oxidative phagocyte killing. In: Scriver CR, Beaudet AL, Sly WS, Valle D, editors. The Metabolic and Molecular Bases of Inherited Disease. 8th ed. http://www.ommbid.com/, New York, McGraw‐Hill, 2001, Chap.189. New York: McGraw‐Hill Inc, Updated October, 2009.
 80. Eckert R. Excitation and luminescence in Noctiluca miliaris. In: Johnson FH, Haneda Y, editors Bioluminescence in Progress, Princeton, NJ: Princeton University Press, 1966, p. 269‐300.
 81. Eckert R. II. Asynchronous flash initiation by a propagated triggering potential. Science 147: 1142‐1145, 1965.
 82. Eckert R, Reynolds GT. The subcellular origin of bioluminescence in Noctiluca miliaris. J Gen Physiol 50: 1429‐1458, 1967.
 83. Eckert R, Sibaoka T. The flash‐triggering action potential of the luminescent dinoflagellate Noctiluca. J Gen Physiol 52: 258‐282, 1968.
 84. Effros RM, Mason G, Silverman P. Asymmetric distribution of carbonic anhydrase in the alveolar‐capillary barrier. J Appl Physiol 51: 190‐193, 1981.
 85. Effros RM, Olson L, Lin W, Audi S, Hogan G, Shaker R, Hoagland K, Foss B. Resistance of the pulmonary epithelium to movement of buffer ions. Am J Physiol Lung Cell Mol Physiol 285: L476‐L483, 2003.
 86. Eigen M, De Maeyer L. Self‐dissociation and protonic charge transport in water and ice. Proc R Soc Lond A 247: 505‐533, 1958.
 87. El Chemaly A, Guinamard R, Demion M, Fares N, Jebara V, Faivre JF, Bois P. A voltage‐activated proton current in human cardiac fibroblasts. Biochem Biophys Res Commun 340: 512‐516, 2006.
 88. El Chemaly A, Okochi Y, Sasaki M, Arnaudeau S, Okamura Y, Demaurex N. VSOP/Hv1 proton channels sustain calcium entry, neutrophil migration, and superoxide production by limiting cell depolarization and acidification. J Exp Med 207: 129‐139, 2010.
 89. Elinder F, Århem P. Metal ion effects on ion channel gating. Q Rev Biophys 36: 373‐427, 2004.
 90. Femling JK, Cherny VV, Morgan D, Rada B, Davis AP, Czirják G, Enyedi P, England SK, Moreland JG, Ligeti E, Nauseef WM, DeCoursey TE. The antibacterial activity of human neutrophils and eosinophils requires proton channels but not BK channels. J Gen Physiol 127: 659‐672, 2006.
 91. Fischer H. Function of proton channels in lung epithelia. WIREs Membr Transp Signal 2011. doi: 10.1002/wmts.17 (In press)
 92. Fischer H, Gonzales LK, Kolla V, Schwarzer C, Miot F, Illek B, Ballard PL. Developmental regulation of DUOX1 expression and function in human fetal lung epithelial cells. Am J Physiol Lung Cell Mol Physiol 292: L1506‐L1514, 2007.
 93. Fischer H, Widdicombe JH. Mechanisms of acid and base secretion by the airway epithelium. J Membr Biol 211: 139‐150, 2006.
 94. Fischer H, Widdicombe JH, Illek B. Acid secretion and proton conductance in human airway epithelium. Am J Physiol Cell Physiol 282: C736‐743, 2002.
 95. Fogel M Hastings JW. A substrate‐binding protein in the Gonyaulax bioluminescence reaction. Arch Biochem Biophys 142: 310‐321, 1971.
 96. Fogel M, Hastings JW. Bioluminescence: Mechanism and mode of control of scintillon activity. Proc Natl Acad Sci U S A 69: 690‐693, 1972.
 97. Forteza R, Salathe M, Miot F, Forteza R, Conner GE. Regulated hydrogen peroxide production by Duox in human airway epithelial cells. Am J Respir Cell Mol Biol 32: 462‐469, 2005.
 98. Frankenhaeuser B, Hodgkin AL. The action of calcium on the electrical properties of squid axons. J Physiol 137: 218‐244, 1957.
 99. Fujiwara Y, Kurokawa T, Takeshita K, Kobayashi M, Nakagawa A, Okamura Y. Stability of the cytoplasmic dimer assembly regulates the thermosensitive gating of the voltage‐gated H+ channel. Biophys J 100: 348a, 2011.
 100. Geiszt M, Kapus A, Nemet K, Farkas L, Ligeti E. Regulation of capacitative Ca2+ influx in human neutrophil granulocytes. Alterations in chronic granulomatous disease. J Biol Chem 272: 26471‐26478, 1997.
 101. Gilly WF, Armstrong CM. Divalent cations and the activation kinetics of potassium channels in squid giant axons. J Gen Physiol 79: 965‐996, 1982.
 102. Goldman DE. Potential, impedance, and rectification in membranes. J Gen Physiol 27: 37‐60, 1943.
 103. Gonzalez C, Koch HP, Drum BM, Larsson HP. Strong cooperativity between subunits in voltage‐gated proton channels. Nat Struct Mol Biol 17: 51‐56, 2010.
 104. Gonzalez C, Rebolledo S, Wang X, Perez M, Larsson HP. Contribution of S4 charges to gating mechanism in Hv channels. Biophys J 100: 173a, 2011.
 105. Gordienko DV, Tare M, Parveen S, Fenech CJ, Robinson C, Bolton TB. Voltage‐activated proton current in eosinophils from human blood. J Physiol 496: 299‐316, 1996.
 106. Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ. Improved patch‐clamp techniques for high‐resolution current recording from cells and cell‐free membrane patches. Pflügers Arch 391: 85‐100, 1981.
 107. Hampton MB, Kettle AJ, Winterbourn CC. Inside the neutrophil phagosome: Oxidants, myeloperoxidase, and bacterial killing. Blood 92: 3007‐3017, 1998.
 108. Hanke W, Miller C. Single chloride channels from Torpedo electroplax. Activation by protons. J Gen Physiol 82: 25‐45, 1983.
 109. Hastings JW. Bacterial and dinoflagellate luminescent systems. In: Herring P, editor. Bioluminescence in Action, London: Academic Press, 1978, p. 129‐170.
 110. Hastings JW. Bioluminescence. In: Sperelakis N, editor. Cell Physiology Sourcebook: A Molecular Approach ( 3rd ed), San Diego: Academic Press, 2001, p. 1115‐1131.
 111. Hastings JW, Vergin M, DeSa R. Scintillons: The biochemistry of dinoflagellate bioluminescence. In: Johnson FH, Haneda Y, editors. Bioluminescence in Progress, Princeton NJ: Princeton University Press, 1966, p. 301‐329.
 112. Henderson LM, Banting G, Chappell JB. The arachidonate‐activable, NADPH oxidase‐associated H+ channel. Evidence that gp91‐phox functions as an essential part of the channel. J Biol Chem 270: 5909‐5916, 1995.
 113. Henderson LM, Chappell JB. The NADPH‐oxidase‐associated H+ channel is opened by arachidonate. Biochem J 283: 171‐175, 1992.
 114. Henderson LM, Chappell JB, Jones OTG. The superoxide‐generating NADPH oxidase of human neutrophils is electrogenic and associated with an H+ channel. Biochem J 246: 325‐329, 1987.
 115. Henderson LM, Chappell JB, Jones OTG. Internal pH changes associated with the activity of NADPH oxidase of human neutrophils. Further evidence for the presence of an H + conducting channel. Biochem J 251: 563‐567, 1988.
 116. Henderson LM, Chappell JB, Jones OTG. Superoxide generation by the electrogenic NADPH oxidase of human neutrophils is limited by the movement of a compensating charge. Biochem J 255: 285‐290, 1988.
 117. Henderson LM, Meech RW. Evidence that the product of the human X‐linked CGD gene, gp91‐phox, is a voltage‐gated H+ pathway. J Gen Physiol 114: 771‐786, 1999.
 118. Henderson LM, Thomas S, Banting G, Chappell JB. The arachidonate‐activatable, NADPH oxidase‐associated H+ channel is contained within the multi‐membrane‐spanning N‐terminal region of gp91‐phox. Biochem J 325: 701‐705, 1997.
 119. Hille B. Ion Channels of Excitable Membranes. Sunderland, MA: Sinauer Associates, Inc, 2001.
 120. Hisada M. Membrane resting and action potentials from a protozoan, Noctiluca scintillans. J Cell Comp Physiol 50: 57‐71, 1957.
 121. Hodgkin AL, Huxley AF. The dual effect of membrane potential on sodium conductance in the giant axon of Loligo. J Physiol 116: 497‐506, 1952.
 122. Hodgkin AL, Huxley AF. A quantitative description of membrane current and its application to conduction and excitation in nerve. J Physiol 117: 500‐544, 1952.
 123. Hodgkin AL, Katz B. The effect of sodium ions on the electrical activity of giant axon of the squid. J Physiol 108: 37‐77, 1949.
 124. Hu F, Luo W, Hong M. Mechanisms of proton conduction and gating in influenza M2 proton channels from solid‐state NMR. Science 330: 505‐508, 2010.
 125. Humez S, Collin T, Matifat F, Guilbault P, Fournier F. InsP3‐dependent Ca2+ oscillations linked to activation of voltage‐dependent H+ conductance in Rana esculenta oocytes. Cell Signal 8: 375‐379, 1996.
 126. Humez S, Fournier F, Guilbault P. A voltage‐dependent and pH‐sensitive proton current in Rana esculenta oocytes. J Membr Biol 147: 207‐215, 1995.
 127. Ilan B, Tajkhorshid E, Schulten K, Voth GA. The mechanism of proton exclusion in aquaporin channels. Proteins 55: 223‐228, 2004.
 128. Iovannisci D, Illek B, Fischer H. Function of the HVCN1 proton channel in airway epithelia and a naturally occurring mutation, M91T. J Gen Physiol 136: 35‐46, 2010.
 129. Iyer GYN, Islam MF, Quastel JH. Biochemical aspects of phagocytosis. Nature 192: 535‐541, 1961.
 130. Jankowski A, Grinstein S. A noninvasive fluorimetric procedure for measurement of membrane potential. Quantification of the NADPH oxidase‐induced depolarization in activated neutrophils. J Biol Chem 274: 26098‐26104, 1999.
 131. Jiang Y, Lee A, Chen J, Ruta V, Cadene M, Chait BT, MacKinnon R. X‐ray structure of a voltage‐dependent K+ channel. Nature 423: 33‐41, 2003.
 132. Jones GS, VanDyke K, Castranova V. Transmembrane potential changes associated with superoxide release from human granulocytes. J Cell Physiol 106: 75‐83, 1981.
 133. Joseph D, Tirmizi O, Zhang XL, Crandall ED, Lubman RL. Polarity of alveolar epithelial cell acid‐base permeability. Am J Physiol Lung Cell Mol Physiol 282: L675‐683, 2002.
 134. Kapus A, Romanek R, Qu AY, Rotstein OD, Grinstein S. A pH‐sensitive and voltage‐dependent proton conductance in the plasma membrane of macrophages. J Gen Physiol 102: 729‐760, 1993.
 135. Kapus A, Suszták K, Ligeti E. Regulation of the electrogenic H+ channel in the plasma membrane of neutrophils: possible role of phospholipase A2, internal and external protons. Biochem J 292: 445‐450, 1993.
 136. Kass I, Arkin IT. How pH opens a H+ channel: The gating mechanism of influenza A M2. Structure 13: 1789‐1798, 2005.
 137. Khurana E, Dal Peraro M, DeVane R, Vemparala S, DeGrado WF, Klein ML. Molecular dynamics calculations suggest a conduction mechanism for the M2 proton channel from influenza A virus. Proc Natl Acad Sci U S A 106: 1069‐1074, 2009.
 138. Klebanoff SJ. Myeloperoxidase: contribution to the microbicidal activity of intact leukocytes. Science 169: 1095‐1097, 1970.
 139. Koch HP, Kurokawa T, Okochi Y, Sasaki M, Okamura Y, Larsson HP. Multimeric nature of voltage‐gated proton channels. Proc Natl Acad Sci U S A 105: 9111‐9116, 2008.
 140. Korchak HM, Weissmann G. Changes in membrane potential of human granulocytes antecede the metabolic responses to surface stimulation. Proc Natl Acad Sci U S A 75: 3818‐3822, 1978.
 141. Krieger N, Hastings JW. Bioluminescence: pH activity profiles of related luciferase fractions. Science 161: 586‐589, 1968.
 142. Kukol A, Adams PD, Rice LM, Brunger AT, Arkin TI. Experimentally based orientational refinement of membrane protein models: A structure for the Influenza A M2 H+ channel. J Mol Biol 286: 951‐962, 1999.
 143. Kumánovics A, Levin G, Blount P. Family ties of gated pores: Evolution of the sensor module. Faseb J 16: 1623‐1629, 2002.
 144. Kuno M, Ando H, Morihata H, Sakai H, Mori H, Sawada M, Oiki S. Temperature dependence of proton permeation through a voltage‐gated proton channel. J Gen Physiol 134: 191‐205, 2009.
 145. Kuno M, Kawawaki J, Nakamura F. A highly temperature‐sensitive proton current in mouse bone marrow‐derived mast cells. J Gen Physiol 109: 731‐740, 1997.
 146. Laggner H, Phillipp K, Goldenberg H. Free zinc inhibits transport of vitamin C in differentiated HL‐60 cells during respiratory burst. Free Radic Biol Med 40: 436‐443, 2006.
 147. Larsson HP, Baker OS, Dhillon DS, Isacoff EY. Transmembrane movement of the shaker K+ channel S4. Neuron 16: 387‐397, 1996.
 148. Lear JD. Proton conduction through the M2 protein of the influenza A virus; a quantitative, mechanistic analysis of experimental data. FEBS Lett 552: 17‐22, 2003.
 149. Lee SC, Steinhardt RA. pH changes associated with meiotic maturation in oocytes of Xenopus laevis. Dev Biol 85: 358‐369, 1981.
 150. Lee SY, Letts JA, Mackinnon R. Dimeric subunit stoichiometry of the human voltage‐dependent proton channel Hv1. Proc Natl Acad Sci U S A 105: 7692‐7695, 2008.
 151. Lee SY, Letts JA, MacKinnon R. Functional reconstitution of purified human Hv1 H+ channels. J Mol Biol 387: 1055‐1060, 2009.
 152. Leiding T, Wang J, Martinsson J, DeGrado WF, Årsköld SP. Proton and cation transport activity of the M2 proton channel from influenza A virus. Proc Natl Acad Sci U S A 107: 15409‐15414, 2010.
 153. Levis RA, Rae JL. The use of quartz patch pipettes for low noise single channel recording. Biophys J 65: 1666‐1677, 1993.
 154. Levitt DG, Elias SR, Hautman JM. Number of water molecules coupled to the transport of sodium, potassium and hydrogen ions via gramicidin, nonactin or valinomycin. Biochim Biophys Acta 512: 436‐451, 1978.
 155. Levy R, Lowenthal A, Dana R. Cytosolic phospholipase A2 is required for the activation of the NADPH oxidase associated H+ channel in phagocyte‐like cells. Adv Exp Med Biol 479: 125‐135, 2000.
 156. Li SJ, Zhao Q, Zhou Q, Unno H, Zhai Y, Sun F. The role and structure of the carboxyl‐terminal domain of the human voltage‐gated proton channel Hv1. J Biol Chem 285: 12047‐12054, 2010.
 157. Lin MC, Hsieh JY, Mock AF, Papazian DM. R1 in the Shaker S4 occupies the gating charge transfer center in the resting state. J Gen Physiol 138: 155‐163.
 158. Lin TI, Schroeder C. Definitive assignment of proton selectivity and attoampere unitary current to the M2 ion channel protein of influenza a virus. J Virol 75: 3647‐3656, 2001.
 159. Lisal J, Maduke M. The ClC‐0 chloride channel is a ‘broken’ Cl−/H+ antiporter. Nat Struct Mol Biol 15: 805‐810, 2008.
 160. Lishko PV, Botchkina IL, Fedorenko A, Kirichok Y. Acid extrusion from human spermatozoa is mediated by flagellar voltage‐gated proton channel. Cell 140: 327‐337, 2010.
 161. Long SB, Tao X, Campbell EB, MacKinnon R. Atomic structure of a voltage‐dependent K+ channel in a lipid membrane‐like environment. Nature 450: 376‐382, 2007.
 162. Lowenthal A, Levy R. Essential requirement of cytosolic phospholipase A2 for activation of the H+ channel in phagocyte‐like cells. J Biol Chem 274: 21603‐21608, 1999.
 163. Ludewig U, Pusch M, Jentsch TJ. Two physically distinct pores in the dimeric ClC‐0 chloride channel. Nature 383: 340‐343, 1996.
 164. MacGlashan D, Jr. Botana LM. Biphasic Ca2+ responses in human basophils. Evidence that the initial transient elevation associated with the mobilization of intracellular calcium is an insufficient signal for degranulation. J Immunol 150: 980‐991, 1993.
 165. Magneson GR, Puvathingal JM, Ray WJ, Jr. The concentrations of free Mg2+ and free Zn2+ in equine blood plasma. J Biol Chem 262: 11140‐11148, 1987.
 166. Mahaut‐Smith MP. The effect of zinc on calcium and hydrogen ion currents in intact snail neurones. J Exp Biol 145: 455‐464, 1989.
 167. Mahaut‐Smith MP. Separation of hydrogen ion currents in intact molluscan neurones. J Exp Biol 145: 439‐454, 1989.
 168. Mankelow TJ, Pessach E, Levy R, Henderson LM. The requirement of cytosolic phospholipase A2 for the PMA activation of proton efflux through the N‐terminal 230‐amino‐acid fragment of gp91phox. Biochem J 374: 315‐319, 2003.
 169. Maturana A, Arnaudeau S, Ryser S, Banfi B, Hossle JP, Schlegel W, Krause KH, Demaurex N. Heme histidine ligands within gp91phox modulate proton conduction by the phagocyte NADPH oxidase. J Biol Chem 276: 30277‐30284, 2001.
 170. Meech RW, Thomas RC. Voltage‐dependent intracellular pH in Helix aspersa neurones. J Physiol 390: 433‐452, 1987.
 171. Middleton RE, Pheasant DJ, Miller C. Homodimeric architecture of a ClC‐type chloride ion channel. Nature 383: 337‐340, 1996.
 172. Miller C. ClC chloride channels viewed through a transporter lens. Nature 440: 484‐489, 2006.
 173. Miller C. Lonely voltage sensor seeks protons for permeation. Science 312: 534‐535, 2006.
 174. Miller C, White MM. A voltage‐dependent chloride conductance channel from Torpedo electroplax membrane. Ann N Y Acad Sci 341: 534‐551, 1980.
 175. Miloshevsky GV, Jordan PC. Water and ion permeation in bAQP1 and GlpF channels: A kinetic Monte Carlo study. Biophys J 87: 3690‐3702, 2004.
 176. Minor DL, Jr. A sensitive channel family replete with sense and motion. Nat Struct Mol Biol 13: 388‐390, 2006.
 177. Mitchell P. Coupling of phosphorylation to electron and hydrogen transfer by a chemi‐osmotic type of mechanism. Nature 191: 144‐148, 1961.
 178. Morgan D, Capasso M, Musset B, Cherny VV, Ríos E, Dyer MJS, DeCoursey TE. Voltage‐gated proton channels maintain pH in human neutrophils during phagocytosis. Proc Natl Acad Sci U S A 106: 18022‐18027, 2009.
 179. Morgan D, Cherny VV, Finnegan A, Bollinger J, Gelb MH, DeCoursey TE. Sustained activation of proton channels and NADPH oxidase in human eosinophils and murine granulocytes requires PKC but not cPLA2α activity. J Physiol 579: 327‐344, 2007.
 180. Morgan D, Cherny VV, Murphy R, Katz BZ, DeCoursey TE. The pH dependence of NADPH oxidase in human eosinophils. J Physiol 569: 419‐431, 2005.
 181. Morgan D, Cherny VV, Price MO, Dinauer MC, DeCoursey TE. Absence of proton channels in COS‐7 cells expressing functional NADPH oxidase components. J Gen Physiol 119: 571‐580, 2002.
 182. Morgan D, DeCoursey TE. Simultaneous measurement of phagosome and plasma membrane potentials in human neutrophils by di‐8‐Anepps and SEER. Biophys J 96: 55a, 2010.
 183. Mori H, Sakai H, Morihata H, Kawawaki J, Amano H, Yamano T, Kuno M. Regulatory mechanisms and physiological relevance of a voltage‐gated H+ channel in murine osteoclasts: Phorbol myristate acetate induces cell acidosis and the channel activation. J Bone Miner Res 18: 2069‐2076, 2003.
 184. Mori H, Sakai H, Morihata H, Yamano T, Kuno M. A voltage‐gated H+ channel is a powerful mechanism for pH homeostasis in murine osteoclasts. Kobe J Med Sci 48: 87‐96, 2002.
 185. Morihata H, Kawawaki J, Okina M, Sakai H, Notomi T, Sawada M, Kuno M. Early and late activation of the voltage‐gated proton channel during lactic acidosis through pH‐dependent and ‐independent mechanisms. Pflügers Arch 455: 829‐838, 2008.
 186. Morihata H, Kawawaki J, Sakai H, Sawada M, Tsutada T, Kuno M. Temporal fluctuations of voltage‐gated proton currents in rat spinal microglia via pH‐dependent and ‐independent mechanisms. Neurosci Res 38: 265‐271, 2000.
 187. Morihata H, Nakamura F, Tsutada T, Kuno M. Potentiation of a voltage‐gated proton current in acidosis‐induced swelling of rat microglia. J Neurosci 20: 7220‐7227, 2000.
 188. Moskwa P, Lorentzen D, Excoffon KJ, Zabner J, McCray PB, Jr, Nauseef WM, Dupuy C, Bánfi B. A novel host defense system of airways is defective in cystic fibrosis. Am J Respir Crit Care Med 175: 174‐183, 2007.
 189. Mould JA, Li HC, Dudlak CS, Lear JD, Pekosz A, Lamb RA, Pinto LH. Mechanism for proton conduction of the M2 ion channel of influenza A virus. J Biol Chem 275: 8592‐8599, 2000.
 190. Murata K, Mitsuoka K, Hirai T, Walz T, Agre P, Heymann JB, Engel A, Fujiyoshi Y. Structural determinants of water permeation through aquaporin‐1. Nature 407: 599‐605, 2000.
 191. Murata Y, Iwasaki H, Sasaki M, Inaba K, Okamura Y. Phosphoinositide phosphatase activity coupled to an intrinsic voltage sensor. Nature 435: 1239‐1243, 2005.
 192. Murphy R, Cherny VV, Morgan D, DeCoursey TE. Voltage‐gated proton channels help regulate pHi in rat alveolar epithelium. Am J Physiol Lung Cell Mol Physiol 288: L398‐L408, 2005.
 193. Murphy R, DeCoursey TE. Charge compensation during the phagocyte respiratory burst. Biochim Biophys Acta 1757: 996‐1011, 2006.
 194. Musset B, Capasso M, Cherny VV, Morgan D, Bhamrah M, Dyer MJS, DeCoursey TE. Identification of Thr29 as a critical phosphorylation site that activates the human proton channel Hvcn1 in leukocytes. J Biol Chem 285: 5117‐5121, 2010.
 195. Musset B, Cherny VV, DeCoursey TE. Strong glucose dependence of electron current in human monocytes. Am J Physiol: Cell Physiol (In press).
 196. Musset B, Cherny VV, Morgan D, DeCoursey TE. The intimate and mysterious relationship between proton channels and NADPH oxidase. FEBS Lett 583: 7‐12, 2009.
 197. Musset B, Cherny VV, Morgan D, Okamura Y, Ramsey IS, Clapham DE, DeCoursey TE. Detailed comparison of expressed and native voltage‐gated proton channel currents. J Physiol 586: 2477‐2486, 2008.
 198. Musset B, Morgan D, Cherny VV, MacGlashan DW, Jr, Thomas LL, Ríos E, DeCoursey TE. A pH‐stabilizing role of voltage‐gated proton channels in IgE‐mediated activation of human basophils. Proc Natl Acad Sci U S A 105: 11020‐11025, 2008.
 199. Musset B, Smith SM, Rajan S, Cherny VV, Morgan D, DeCoursey TE. Oligomerization of the voltage gated proton channel. Channels (Austin) 4: 260‐265, 2010.
 200. Musset B, Smith SM, Rajan S, Cherny VV, Sujai S, Morgan D, DeCoursey TE. Zinc inhibition of monomeric and dimeric proton channels suggests cooperative gating. J Physiol 588: 1435‐1449, 2010.
 201. Musset B, Smith SME, Rajan S, Morgan D, Cherny VV, DeCoursey TE. Aspartate112 is the selectivity filter of the human voltage gated proton channel. Nature doi: 10.1038/nature10557, 2011.
 202. Myers VB, Haydon DA. Ion transfer across lipid membranes in the presence of gramicidin A: The ion selectivity. Biochim Biophys Acta 274: 313‐322, 1972.
 203. Nagle JF Morowitz HJ. Molecular mechanisms for proton transport in membranes. Proc Natl Acad Sci U S A 75: 298‐302, 1978.
 204. Nanda A, Grinstein S, Curnutte JT. Abnormal activation of H+ conductance in NADPH oxidase‐defective neutrophils. Proc Natl Acad Sci U S A 90: 760‐764, 1993.
 205. Nanda A, Romanek R, Curnutte JT, Grinstein S. Assessment of the contribution of the cytochrome b moiety of the NADPH oxidase to the transmembrane H+ conductance of leukocytes. J Biol Chem 269: 27280‐27285, 1994.
 206. Nawata T, Sibaoka T. Ionic composition and pH of the vacuolar sap in marine dinoflagellate Noctiluca. Plant Cell Physiol 17: 265‐272, 1976.
 207. Nawata T Sibaoka T. Coupling between action potential and bioluminescence in Noctiluca: Effects of inorganic ions and pH in vacuolar sap. J Comp Physiol 134: 137‐149, 1979.
 208. Nelson RD, Kuan G, Saier MH, Jr, Montal M. Modular assembly of voltage‐gated channel proteins: A sequence analysis and phylogenetic study. J Mol Microbiol Biotechnol 1: 281‐287, 1999.
 209. Ng AW, Bidani A, Heming TA. Innate host defense of the lung: effects of lung‐lining fluid pH. Lung 182: 297‐317, 2004.
 210. Nicolas MT, Sweeney BM, Hastings JW. The ultrastructural localization of luciferase in three bioluminescent dinoflagellates, two species of Pyrocystis, and Noctiluca, using anti‐luciferase and immunogold labelling. J Cell Sci 87: 189‐196, 1987.
 211. Nielson DW, Goerke J, Clements JA. Alveolar subphase pH in the lungs of anesthetized rabbits. Proc Natl Acad Sci U S A 78: 7119‐7123, 1981.
 212. Nordström T, Rotstein OD, Romanek R, Asotra S, Heersche JN, Manolson MF, Brisseau GF, Grinstein S. Regulation of cytoplasmic pH in osteoclasts. Contribution of proton pumps and a proton‐selective conductance. J Biol Chem 270: 2203‐2212, 1995.
 213. Oami K. Correlation between membrane potential responses and tentacle movement in the dinoflagellate Noctiluca miliaris. Zoolog Sci 21: 131‐138, 2004.
 214. Okochi Y, Sasaki M, Iwasaki H, Okamura Y. Voltage‐gated proton channel is expressed on phagosomes. Biochem Biophys Res Commun 382: 274‐279, 2009.
 215. Pantazis A, Keegan P, Postma M, Schwiening CJ. The effect of neuronal morphology and membrane‐permeant weak acid and base on the dissipation of depolarization‐induced pH gradients in snail neurons. Pflügers Arch 452: 175‐187, 2006.
 216. Peterson E, Ryser T, Funk S, Inouye D, Sharma M, Qin H, Cross TA, Busath DD. Functional reconstitution of influenza A M2(22‐62). Biochim Biophys Acta 1808: 516‐521, 2011.
 217. Petheő GL, Demaurex N. Voltage‐ and NADPH‐dependence of electron currents generated by the phagocytic NADPH oxidase. Biochem J 388: 485‐491, 2005.
 218. Petheő GL, Orient A, Baráth M, Kovács I, Réthi B, Lányi A, Rajki A, Rajnavölgyi E, Geiszt M. Molecular and functional characterization of HV1 proton channel in human granulocytes. PLoS One 5: e14081, 2010.
 219. Pinto LH, Dieckmann GR, Gandhi CS, Papworth CG, Braman J, Shaughnessy MA, Lear JD, Lamb RA, DeGrado WF. A functionally defined model for the M2 proton channel of influenza A virus suggests a mechanism for its ion selectivity. Proc Natl Acad Sci U S A 94: 11301‐11306, 1997.
 220. Qiu ZH, Leslie CC. Protein kinase C‐dependent and ‐independent pathways of mitogen‐activated protein kinase activation in macrophages by stimuli that activate phospholipase A2. J Biol Chem 269: 19480‐19487, 1994.
 221. de Quatrefages A. Observations sur les noctiluques. Annales des Sciences Naturelles, Series 3, Zoologie 14: 226‐235, 1850.
 222. Rada B, Lekstrom K, Damian S, Dupuy C, Leto TL. The Pseudomonas toxin pyocyanin inhibits the dual oxidase‐based antimicrobial system as it imposes oxidative stress on airway epithelial cells. J Immunol 181: 4883‐4893, 2008.
 223. Rada BK, Geiszt M, Káldi K, Tímár C, Ligeti E. Dual role of phagocytic NADPH oxidase in bacterial killing. Blood 104: 2947‐2953, 2004.
 224. Ramsey IS, Mokrab Y, Carvacho I, Sands ZA, Sansom MSP, Clapham DE. An aqueous H+ permeation pathway in the voltage‐gated proton channel Hv1. Nat Struct Mol Biol 17: 869‐875, 2010.
 225. Ramsey IS, Moran MM, Chong JA, Clapham DE. A voltage‐gated proton‐selective channel lacking the pore domain. Nature 440: 1213‐1216, 2006.
 226. Ramsey IS, Ruchti E, Kaczmarek JS, Clapham DE. Hv1 proton channels are required for high‐level NADPH oxidase‐dependent superoxide production during the phagocyte respiratory burst. Proc Natl Acad Sci U S A 106: 7642‐7647, 2009.
 227. Reeves EP, Lu H, Jacobs HL, Messina CG, Bolsover S, Gabella G, Potma EO, Warley A, Roes J, Segal AW. Killing activity of neutrophils is mediated through activation of proteases by K+ flux. Nature 416: 291‐297, 2002.
 228. Reth M, Dick TP. Voltage control for B cell activation. Nat Immunol 11: 191‐192, 2010.
 229. Roos A, Boron WF. Intracellular pH. Physiol Rev 61: 296‐434, 1981.
 230. Saaranen M, Suistomaa U, Kantola M, Saarikoski S, Vanha‐Perttula T. Lead, magnesium, selenium and zinc in human seminal fluid: comparison with semen parameters and fertility. Hum Reprod 2: 475‐479, 1987.
 231. Sakata S, Kurokawa T, Norholm MH, Takagi M, Okochi Y, von Heijne G, Okamura Y. Functionality of the voltage‐gated proton channel truncated in S4. Proc Natl Acad Sci U S A 107: 2313‐2318, 2010.
 232. Sánchez JC, Powell T, Staines HM, Wilkins RJ. Electrophysiological demonstration of voltage‐ activated H+ channels in bovine articular chondrocytes. Cell Physiol Biochem 18: 85‐90, 2006.
 233. Sánchez JC, Wilkins RJ. Effects of hypotonic shock on intracellular pH in bovine articular chondrocytes. Comp Biochem Physiol A Mol Integr Physiol 135: 575‐583, 2003.
 234. Sansom MSP, Kerr ID, Smith GR, Son HS. The influenza A virus M2 channel: A molecular modeling and simulation study. Virology 233: 163‐173, 1997.
 235. Sasaki M, Takagi M, Okamura Y. A voltage sensor‐domain protein is a voltage‐gated proton channel. Science 312: 589‐592, 2006.
 236. Sbarra AJ, Karnovsky ML. The biochemical basis of phagocytosis. I. Metabolic changes during the ingestion of particles by polymorphonuclear leukocytes. J Biol Chem 234: 1355‐1362, 1959.
 237. Schilling T, Gratopp A, DeCoursey TE, Eder C. Voltage‐activated proton currents in human lymphocytes. J Physiol 545: 93‐105, 2002.
 238. Schmitter RE, Njus D, Sulzman FM, Gooch VD, Hastings JW. Dinoflagellate bioluminescence: a comparative study of in vitro components. J Cell Physiol 87: 123‐134, 1976.
 239. Schowen RL. Solvent Isotope Effects on Enzymic Reactions. In: Cleland WW, O'Leary MH, Northrop DB, editors. Isotope Effects on Enzyme‐Catalyzed Reactions, Baltimore: University Park Press, 1977, p. 64‐99.
 240. Schrenzel J, Lew DP, Krause KH. Proton currents in human eosinophils. Am J Physiol 271: C1861‐C1871, 1996.
 241. Schwarzer C, Machen TE, Illek B, Fischer H. NADPH oxidase‐dependent acid production in airway epithelial cells. J Biol Chem 279: 36454‐36461, 2004.
 242. Schweighofer KJ, Pohorille A. Computer simulation of ion channel gating: The M2 channel of influenza A virus in a lipid bilayer. Biophys J 78: 150‐163, 2000.
 243. Schwiening CJ, Willoughby D. Depolarization‐induced pH microdomains and their relationship to calcium transients in isolated snail neurones. J Physiol 538: 371‐382, 2002.
 244. Seeds MC, Parce JW, Szejda P, Bass DA. Independent stimulation of membrane potential changes and the oxidative metabolic burst in polymorphonuclear leukocytes. Blood 65: 233‐240, 1985.
 245. Sesti F, Goldstein SA. Single‐channel characteristics of wild‐type IKs channels and channels formed with two minK mutants that cause long QT syndrome. J Gen Physiol 112: 651‐663, 1998.
 246. Sharma M, Yi M, Dong H, Qin H, Peterson E, Busath D, Zhou H, Cross T. Insight into the mechanism of the influenza A proton channel from structure in a lipid bilayer. Science 330: 509‐512, 2010.
 247. Sheldon C, Church J. Intracellular pH response to anoxia in acutely dissociated adult rat hippocampal CA1 neurons. J. Neurophysiol 87: 2209‐2224, 2002.
 248. Sheng J, Malkiel E, Katz J, Adolf JE, Place AR. A dinoflagellate exploits toxins to immobilize prey prior to ingestion. Proc Natl Acad Sci U S A 107: 2082‐2087, 2010.
 249. Shuck K, Lamb RA, Pinto LH. Analysis of the pore structure of the influenza A virus M2 ion channel by the substituted‐cysteine accessibility method. J Virol 74: 7755‐7761, 2000.
 250. Sklar LA, Jesaitis AJ, Painter RG, Cochrane CG. The kinetics of neutrophil activation. The response to chemotactic peptides depends upon whether ligand‐receptor interaction is rate‐limiting. J Biol Chem 256: 9909‐9914, 1981.
 251. Smith SME, Morgan D, Musset B, Cherny VV, Place AR, Hastings JW, DeCoursey TE. A novel voltage gated proton channel in a dinoflagellate. Biophys J 100: 284a. 2011
 252. Smith SME, Morgan D, Musset B, Cherny VV, Place AR, Hastings JW, DeCoursey TE. Voltage‐gated proton channel in a dinoflagellate. Proc Natl Acad Sci U S A 108: 18162‐18168, 2011.
 253. Smondyrev AM, Voth GA. Molecular dynamics simulation of proton transport near the surface of a phospholipid membrane. Biophys J 82: 1460‐1468, 2002.
 254. Starace DM, Stefani E, Bezanilla F. Voltage‐dependent proton transport by the voltage sensor of the Shaker K+ channel. Neuron 19: 1319‐1327, 1997.
 255. Suszták K, Mócsai A, Ligeti E, Kapus A. Electrogenic H+ pathway contributes to stimulus‐induced changes of internal pH and membrane potential in intact neutrophils: Role of cytoplasmic phospholipase A2. Biochem J 325: 501‐510, 1997.
 256. Swenson ER, Deem S, Kerr ME, Bidani A. Inhibition of aquaporin‐mediated CO2 diffusion and voltage‐gated H+ channels by zinc does not alter rabbit lung CO2 and NO excretion. Clin Sci (Lond) 103: 567‐575, 2002.
 257. Tajkhorshid E, Nollert P, Jensen MO, Miercke LJ, O'Connell J, Stroud RM, Schulten K. Control of the selectivity of the aquaporin water channel family by global orientational tuning. Science 296: 525‐530, 2002.
 258. Takanaka K, O'Brien PJ. Proton release associated with respiratory burst of polymorphonuclear leukocytes. J Biochem 103: 656‐660, 1988.
 259. Tao X, Lee A, Limapichat W, Dougherty DA, MacKinnon R. A gating charge transfer center in voltage sensors. Science 328: 67‐73, 2010.
 260. Taylor AR, Chrachri A, Wheeler G, Goddard H, Brownlee C. A voltage‐gated H+ channel underlying pH homeostasis in calcifying coccolithophores. PLoS Biol 9: e1001085, 2011.
 261. Thomas RC, Meech RW. Hydrogen ion currents and intracellular pH in depolarized voltage‐clamped snail neurones. Nature 299: 826‐828, 1982.
 262. Tombola F, Ulbrich MH, Isacoff EY. The voltage‐gated proton channel Hv1 has two pores, each controlled by one voltage sensor. Neuron 58: 546‐556, 2008.
 263. Tombola F, Ulbrich MH, Kohout SC, Isacoff EY. The opening of the two pores of the Hv1 voltage‐gated proton channel is tuned by cooperativity. Nat Struct Mol Biol 17: 44‐50, 2010.
 264. Turekian KK. Oceans: Prentice‐Hall, Englewood Cliffs, N.J. 1968.
 265. Urbach V, Helix N, Renaudon B, Harvey BJ. Cellular mechanisms for apical ATP effects on intracellular pH in human bronchial epithelium. J Physiol 543: 13‐21, 2002.
 266. van Zwieten R, Wever R, Hamers MN, Weening RS, Roos D. Extracellular proton release by stimulated neutrophils. J Clin Invest 68: 310‐313, 1981.
 267. Wang Y, Li SJ, Pan J, Che Y, Yin J, Zhao Q. Specific expression of the human voltage‐gated proton channel Hv1 in highly metastatic breast cancer cells, promotes tumor progression and metastasis. Biochem Biophys Res Commun 412: 353‐359, 2011.
 268. Warner JA, MacGlashan DW, Jr. Signal transduction events in human basophils. A comparative study of the role of protein kinase C in basophils activated by anti‐IgE antibody and formyl‐methionyl‐leucyl‐phenylalanine. J Immunol 145: 1897‐1905, 1990.
 269. Whitin JC, Chapman CE, Simons ER, Chovaniec ME, Cohen HJ. Correlation between membrane potential changes and superoxide production in human granulocytes stimulated by phorbol myristate acetate. Evidence for defective activation in chronic granulomatous disease. J Biol Chem 255: 1874‐1878, 1980.
 270. Wikström M, Verkhovsky MI, Hummer G. Water‐gated mechanism of proton translocation by cytochrome c oxidase. Biochim Biophys Acta 1604: 61‐65, 2003.
 271. Wood ML, Schow EV, Freites JA, White SH, Tombola F, Tobias DJ. Water wires in atomistic models of the Hv1 proton channel. Biochim Biophys Acta, 2011 doi:10.1016/j.bbamem.2011.07.045 [Epub ahead of print].
 272. Woodward OM, Willows AO. Dopamine modulation of Ca2+ dependent Cl− current regulates ciliary beat frequency controlling locomotion in Tritonia diomedea. J Exp Biol 209: 2749‐2764, 2006.
 273. Wraight CA. Chance and design–proton transfer in water, channels and bioenergetic proteins. Biochim Biophys Acta 1757: 886‐912, 2006.
 274. Wu B, Steinbronn C, Alsterfjord M, Zeuthen T, Beitz E. Concerted action of two cation filters in the aquaporin water channel. Embo J 28: 2188‐2194, 2009.
 275. Yamaguchi S, Miura C, Kikuchi K, Celino FT, Agusa T, Tanabe S, Miura T. Zinc is an essential trace element for spermatogenesis. Proc Natl Acad Sci U S A 106: 10859‐10864, 2009.
 276. Yang N, George AL, Jr, Horn R. Molecular basis of charge movement in voltage‐gated sodium channels. Neuron 16: 113‐122, 1996.
 277. Yusaf SP, Wray D, Sivaprasadarao A. Measurement of the movement of the S4 segment during the activation of a voltage‐gated potassium channel. Pflügers Arch 433: 91‐97, 1996.
Further Reading
 1. Bezanilla F. The voltage sensor in voltage‐dependent ion channels. Physiol Rev 80: 555‐592, 2000.
 2. Börjesson, SI, Elinder F. Structure, function, and modification of the voltage sensor in voltage‐gated ion channels. Cell Biochem Biophys 52: 149‐174, 2008.
 3. Swartz KJ. Sensing voltage across lipid membranes. Nature 456: 891‐897, 2008.
 4. Tombola F, Pathak MM, Isacoff EY. How does voltage open an ion channel? Annu Rev Cell Dev Biol 22: 23‐52, 2006.
 5. Capasso M, DeCoursey TE, Dyer MJS. pH regulation and beyond: Unanticipated functions for the voltage‐gated proton channel, HVCN1. Trends Cell Biol. 21: 20‐28, 2011.
 6. DeCoursey TE. Voltage‐gated proton channels and other proton transfer pathways. Physiol Rev 83: 475‐579, 2003.
 7.Demaurex N, El Chemaly A. Physiological roles of voltage‐gated proton channels in leukocytes. J Physiol 588: 4659‐4665, 2010.
 8.Kirichok, Y, Lishko PV. Rediscovering sperm ion channels with the patch‐clamp technique. Mol Hum Reprod 17: 478‐499, 2011.
 9. Fischer, H. Function of proton channels in lung epithelia. WIRES Membr Transp Signal (in press), 2011. doi: 10.1002/wmts.17
 10. Hille B. 2001. Ion Channels of Excitable Membranes. (3rd ed). Sunderland, MA: Sinauer Associates, Inc. p. 814.
 11.Okamura Y, Murata Y, Iwasaki H. Voltage‐sensing phosphatase: Actions and potentials. J Physiol 587: 513‐520, 2009.
 12.Okamura Y. Biodiversity of voltage sensor domain proteins. Pflügers Arch 454: 361‐371, 2007.

Further Reading 

Reviews of voltage sensing mechanisms in ion channels:

Bezanilla F. The voltage sensor in voltage-dependent ion channels. Physiol Rev 80: 555-592, 2000.

Börjesson, S.I., and F. Elinder. 2008. Structure, function, and modification of the voltage sensor in voltage-gated ion channels. Cell. Biochem. Biophys. 52:149-174.

Swartz KJ. Sensing voltage across lipid membranes. Nature 456: 891-897, 2008.

Tombola F, Pathak MM, and Isacoff EY. How does voltage open an ion channel? Annu Rev Cell Dev Biol 22: 23-52, 2006.

A recent update on proposed functions of proton channels in various cells:

Capasso M, DeCoursey TE, Dyer MJS.  pH regulation and beyond: unanticipated functions for the voltage-gated proton channel, HVCN1.  Trends Cell Biol.  21:20-28, 2011.  doi:10.1016/j.tcb.2010.09.006

This exhaustive review of voltage-gated proton channels includes comparisons with several other proton conducting molecules:

DeCoursey TE. Voltage-gated proton channels and other proton transfer pathways. Physiol Rev 83: 475-579, 2003.

A recent review of functions of proton channels in phagocytes:

Demaurex N, and El Chemaly A. Physiological roles of voltage-gated proton channels in leukocytes. J Physiol 588:4659-4665, 2010.  doi: 10.1113/jphysiol.2010.194225

A recent focused review of functions of proton channels in sperm:

Kirichok, Y., and P.V. Lishko. 2011. Rediscovering sperm ion channels with the patch-clamp technique. Mol. Hum. Reprod. 17:478-499.

A recent review of functions of proton channels in epithelium:

Fischer, H. 2011. Functions of proton channels in epithelial cells. WIRES Membrane Transport and Signaling. In press.

This is the classic textbook on ion channels:

Hille B. 2001. Ion Channels of Excitable Membranes. 3rd ed. Sinauer Associates, Inc. Sunderland, MA. 814 pp.

Reviews of voltage-sensing phosphatases:

Okamura Y, Murata Y, Iwasaki H. Voltage-sensing phosphatase: actions and potentials. J Physiol 587: 513-520, 2009.

Okamura Y. Biodiversity of voltage sensor domain proteins. Pflügers Arch 454: 361-371, 2007.

 


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How to Cite

Thomas E. DeCoursey. Voltage‐Gated Proton Channels. Compr Physiol 2012, 2: 1355-1385. doi: 10.1002/cphy.c100071