Comprehensive Physiology Wiley Online Library

Exocytosis and Synaptic Vesicle Function

Full Article on Wiley Online Library



Abstract

Synaptic vesicles release their vesicular contents to the extracellular space by Ca2+‐triggered exocytosis. The Ca2+‐triggered exocytotic process is regulated by synaptotagmin (Syt), a vesicular Ca2+‐binding C2 domain protein. Synaptotagmin 1 (Syt1), the most studied major isoform among 16 Syt isoforms, mediates Ca2+‐triggered synaptic vesicle exocytosis by interacting with the target membranes and SNARE/complexin complex. In synapses of the central nervous system, synaptobrevin 2, a major vesicular SNARE protein, forms a ternary SNARE complex with the plasma membrane SNARE proteins, syntaxin 1 and SNAP25. The affinities of Ca2+‐dependent interactions between Syt1 and its targets (i.e., SNARE complexes and membranes) are well correlated with the efficacies of the corresponding exocytotic processes. Therefore, different SNARE protein isoforms and membrane lipids, which interact with Syt1 with various affinities, are capable of regulating the efficacy of Syt1‐mediated exocytosis. Otoferlin, another type of vesicular C2 domain protein that binds to the membrane in a Ca2+‐dependent manner, is also involved in the Ca2+‐triggered synaptic vesicle exocytosis in auditory hair cells. However, the functions of otoferlin in the exocytotic process are not well understood. In addition, at least five different types of synaptic vesicle proteins such as synaptic vesicle protein 2, cysteine string protein α, rab3, synapsin, and a group of proteins containing four transmembrane regions, which includes synaptophysin, synaptogyrin, and secretory carrier membrane protein, are involved in modulating the exocytotic process by regulating the formation and trafficking of synaptic vesicles. © 2014 American Physiological Society. Compr Physiol 4:149‐175, 2014.

Comprehensive Physiology offers downloadable PowerPoint presentations of figures for non-profit, educational use, provided the content is not modified and full credit is given to the author and publication.

Download a PowerPoint presentation of all images


Figure 1. Figure 1. Synaptic vesicle proteins that are involved in regulating Ca2+‐triggered exocytotic processes. The domain structures of synaptic vesicle proteins, which are involved in Ca2+‐triggered exocytotic processes, are illustrated with a brief description of their major functions. The number in parentheses is the average copy number of protein per synaptic vesicle (). Syt1, synaptotagmin 1; SV2, synaptic vesicle protein 2; SCAMP, secretory carrier membrane protein; Syb2, synaptobrevin 2 (also known as VAMP2); CSPα, cysteine string protein α; CaMKs, Ca2+/calmodulin‐dependent protein kinases; GAP, GTPase‐activating protein; GEF, guanine nucleotide exchange factor; PS, phosphatidylserine; PI, phosphatidylinositol; PIP2, phosphatidylinositol 4,5‐bisphosphate. Synapsin interacts with the acidic synaptic vesicle membrane in a phosphorylation/dephosphorylation‐dependent manner (), while rab3a is associated with synaptic vesicles in a GTP‐dependent manner (). The transmembrane region of Syb2 is associated with synaptophysin in the presence of cholesterol ().
Figure 2. Figure 2. Ca2+‐tiggered exocytosis regulated by synaptotagmin 1 (Syt1). (A) Synaptotagmin 1 (Syt1) interacts with the target membrane by electrostatic and van der Waals interactions in a Ca2+‐dependent manner to mediate exocytosis (). The R233 residue of the Syt1C2A domain and the K326, K327, R398, and R399 residues of the Syt1C2B domain are identified as critical residues for electrostatic interaction with membranes for the Syt1 function (). The M173, F234 residues of the Syt1C2A domain and the V304 and I367 residues of the Syt1C2B domain penetrate into the membrane and form van der Waals interaction with hydrophobic lipids of the membrane (). Syt1 also interacts with assembled SNARE complex composed of synaptobrevin 2 (Syb2), syntaxin 1 (Synt1), and SNAP25 (). The Ca2+‐dependent interaction among Syt1, SNARE complex, and membranes are important to mediate the synaptic vesicle exocytosis (), but the molecular mechanism of the interaction is not fully appreciated. (B) The domain structures of Syt1, Syb2, syntaxin 1A (Synt1A), SNAP25, and ferlins. SNAP25 is located in the plasma membrane, without transmembrane region, via palmitoylated C85, C88, C90, and C92 residues between the N‐terminal and C‐terminal SNARE motifs (). The N‐terminal Habc domain () of Synt1A is capable of interacting with the SNARE motif of Synt1A, which hinders the efficient formation of ternary SNARE complex composed of Synt1A, Syb2, and SNAP25. Otoferlin is involved in regulating the Ca2+‐triggered synaptic vesicle exocytosis at synapses of auditory hair cells, where presynaptic SNARE proteins such as Synt1, SNAP25, and Syb2 are not expressed (). However, unlike Syt1, the functions of otoferlin are not clearly demonstrated. Dysferlin, an isoform of otoferlin, regulates Ca2+‐dependent sarcolemma resealing which is mediated by an exocytotic process (). Both otoferlin and dysferlin are probably involved in mediating Ca2+‐triggered exocytotic process by a similar mechanism, which is different from that of Syt1.
Figure 3. Figure 3. Mechanisms of the Ca2+‐dependent synaptotagmin 1 (Syt1) C2 domain binding to the membrane. (A) The Ca2+‐binding loops of the Syt1C2A and Syt1C2B domains. Aspartate (D) residues that directly interact with Ca2+ are indicated by red color, R233 residue that interacts with acidic head groups of phospholipids in the membrane is indicated by white color, and hydrophobic residues that penetrate into the phospholipid bilayer are indicated by blue color. (B) The hydrophobic residues of the synaptotagmin (Syt) C2A and C2B domains, which directly penetrate into the membrane and form van der Waals interaction with hydrophobic lipids. The Ca2+ affinities of the isolated C2 domains were measured in the presence of acidic‐liposomes reconstituted with 75% phosphatidylcholine (PC) and 25% phosphatidylserine (PS) (). (C) The Ca2+ affinities and total amount of the wild‐type and mutant forms of Syt1C2A/B domain binding to synaptic‐liposomes (41% phosphatidylcholine, 32% phosphatidylethanolamine, 12% phosphatidylserine, 5% phosphatidylinositol, and 10% cholesterol) containing 0.25% phosphatidylinositol phosphate (PIP) and 0.05% phosphatidylinositol 4,5‐bisphosphate (PIP2) (). The number in parentheses is an EC50 value of Ca2+ concentration for the Syt1 cytosolic fraction binding to synaptic‐liposomes containing 0.5% PIP and 0.1% PIP2 ().
Figure 4. Figure 4. Regulation of the interaction between synaptotagmin 1 (Syt1) and the membrane by acidic‐phospholipids. (A) Acidic phospholipids such as phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylinositol phosphate (PIP), and phosphatidylinositol 4,5‐bisphosphate (PIP2) are essential for the efficient Ca2+ binding to the C2 domains of synaptotagmin 1 (Syt1). The R233 residue of the Syt1C2A domain, and the K326 and K327 residues of the Syt1C2B domain are important for the efficient Syt1 binding to the membrane in a Ca2+‐dependent manner (). In addition, the R398 and R399 residues of the Syt1C2B domain are essential for the Syt1 function that mediates Ca2+‐triggered exocytosis (). These basic residues interact with acidic head groups of phospholipids in the membrane. Neurons increase PIP, PIP2, and inositol hexakisphosphate (IP6) concentrations by multiple action potential‐stimulations. IP6, a PIP2 metabolite inhibits the function of Syt1 by interacting with the Ca2+‐binding loops of the Syt1C2B domain (). DAG, diacylglycerol. (B) The hydrophilic head groups of PI, PS, and PIP2. The Ca2+ affinity of Syt1 for the membrane binding depends on the acidity of the membrane (). Therefore, PIP2 is much better than PI and PS for the Ca2+‐dependent Syt1 binding to the membrane. Even though the net acidities are the same between PS and PI, PS is better than PI for the Ca2+‐dependent Syt1 binding to the membrane ().
Figure 5. Figure 5. The mechanisms of synaptic vesicle docking, which are mediated by synaptobrevin 2 (Syb2) and synaptotagmin 1 (Syt1). Synaptobrevin 2 (Syb2) is capable of interacting with syntaxin 1 (Synt1)/SNAP25 duplex (), and the basic residues of the Syt1C2B domain are also capable of interacting with either PIP2 in the plasma membrane or Synt1/SNAP25 duplex (). These Ca2+‐independent interactions lead to the synaptic vesicle docking and priming to the target plasma membrane. The primed synaptic vesicles are ready for Ca2+‐triggered exocytosis by extracellular Ca2+ influx after action potential‐stimulations. Neurons lacking Syb2 showed about tenfold decrease in the size of readily releasable pool (RRP), which is affected by the synaptic vesicle priming and docking (). However, neurons expressing Syt1K326A,K327A did not alter the RRP size compared to that of neurons expressing wild‐type Syt1 (). Therefore, the role of the Syt1C2B domain in mediating synaptic vesicle docking and priming is not universally accepted.
Figure 6. Figure 6. Different modes of neurotransmitter release at presynaptic terminals. Three different modes of neurotransmitter release are illustrated (). Action potentials trigger extracellular Ca2+ influx into the presynaptic terminals, and neurotransmitters are released by synchronous or asynchronous modes. Neurons also spontaneously release neurotransmitters without action potentials, but mainly in a Ca2+‐dependent manner (). Ca2+ from either intracellular storages or local Ca2+ channel opening triggers spontaneous mini release. PIP2, phosphatidylinositol 4,5‐bisphosphate; DAG, diacylglycerol; IP3, inositol 1,4,5‐triphosphate; Syt, synaptotagmin; Doc2, double C2 protein; Syb, synaptobrevin (also known as vesicle‐associated membrane protein, VAMP); Vti1a, Vps10p‐tail‐interactor‐1a.
Figure 7. Figure 7. Comparison of amino acid sequences of the synaptotagmin 7 C2A/B (Syt7C2A/B) domains from zebrafish, mouse, rat, and human. Amino acid sequences of the Syt7C2A/B domains from zebrafish (genebank accession # NM_001245957), mouse (genebank accession # NM_173068), rat (genebank accession # NM_021659), and human (genebank accession # NM_004200). The residues that are not conserved in zebrafish are indicated by yellow color. Conserved residues among different species are indicated by grey boxes, and identical residues are not shown. Aspartate residues that directly interact with Ca2+ are indicated by red color.
Figure 8. Figure 8. Domain structures of the synaptic vesicle proteins that have four transmembrane regions. (A) Synaptophysin, synaptogyrin, and secretory carrier membrane protein (SCAMP) have four transmembrane regions. Synaptophysin has four isoforms—synaptophysin 1, synaptophysin 2 (also known as synaptoporin), pantophysin, and mitsugumin 29. Synaptogyrin has three isoforms (synaptogyrin 1‐3), and SCAMP has five isoforms (SCAMP 1‐5). NGly, N‐glycosylation site; Syb2, synaptobrevin 2; Synt1, syntaxin 1; PIP2, phosphatidylinositol 4,5‐bisphosphate; Syt, synaptotagmin; [P]n, multiple phosphorylation sites. (B) Synaptophysin 1 is capable of interacting with either dynamin or Syb2 (), while SCAMP1 is capable of interacting with intersectin1 and γ‐synergin (). Intersectin 1 and γ‐synergin are involved in the endocytotic process in the plasma membrane and vesicle formation in the trans‐Golgi complex, respectively. Therefore, the main function of these proteins in exocytotic processes is probably the generation of releasable synaptic vesicles, which is important for the synaptic facilitation and long‐term potentiation (LTP).
Figure 9. Figure 9. Domain structure of synapsin and its proposed mechanism of synaptic vesicle mobilization. (A) Conserved domains among synapsin isoforms. Phosphorylation sites of synapsin 1a are indicated by “P” in the circle. In particular, the phosphorylation sites by Ca2+/calmodulin‐dependent protein kinases (CaMKs) are indicated by red circles. The “A” domain is capable of interacting with the acidic synaptic vesicle membrane, but phosphorylation of serine9 residue in the “A” domain triggers the dissociation of synapsin from synaptic vesicles. The “C” domain is capable of interacting with the synaptic vesicle membrane and actin filaments, while the “D” domain can interact with SH3‐proteins. Both “C” and “E” domains are involved in synapsin oligomerization. (B) The proposed mechanism of synaptic vesicle mobilization by synapsin 1a and CaMKs (). Repeated stimulations of neurons increase the intracellular Ca2+ concentration, and subsequently activate CaMKs in presynaptic terminals. Activated CaMKs phosphorylate synapsin 1a, and phosphorylated synapsins are dissociated from the cluster composed of synaptic vesicles, synapsin, and actin filaments. This mobilizes synaptic vesicles for exocytosis from the synapsin/CaMK‐responsive synaptic vesicle pools.
Figure 10. Figure 10. Domain structure of cysteine string protein (CSP) and its function in synaptic vesicle trafficking. (A) The domain structure of CSP isoforms. CSPα is capable of interacting with various types of proteins such as synaptotagmin 1 (Syt1), the C2A domain of synaptotagmin 9 (Syt9C2A), SNAP25, syntaxin (Synt), synaptobrevin 2 (Syb2), small glutamine‐rich TPR protein (SGT), GTP‐binding protein (Gαβγ), and N‐type Ca2+ channel. PKA, protein kinase A; PKB, protein kinase B; HIP14, huntingtin‐interacting protein 14. (B) The major function of CSPα, as a component of the chaperone complex composed of Hsc70 and SGT, is the maintenance of the expression levels of SNAP25 and dynamin 1 (). Both SNAP25 and dynamin 1 play critical roles in synaptic vesicle exocytosis and endocytosis.
Figure 11. Figure 11. Mechanism of the rab3‐mediated synaptic vesicle priming to the active zone in the plasma membrane. Rab3a, rab3b, rab3c, and rab27b are expressed in synaptic vesicles (). GTP‐bound form of rab3/rab27b interacts with both RIM and Munc13 proteins (). RIM protein is a component of the presynaptic active zone protein complex (). Munc13 is located in presynaptic active zone and binds to plasma membrane in a Ca2+/diacylglycerol (DAG)‐dependent manner (). Solid line between proteins represents an interaction. Munc13 also stimulates the SNARE complex formation that mediates exocytosis. RIM‐BP, RIM‐binding protein; DAG, diacylglycerol; PIP2, phosphatidylinositol 4,5‐bisphosphate.
Figure 12. Figure 12. The effects of cholesterol and phosphatidylethanolamine (PE) on the Ca2+‐dependent synaptotagmin 1 (Syt1)‐binding to the membrane. Phosphatidylethanolamine (PE) and cholesterol enhanced the Ca2+‐dependent Syt1C2A/B domain binding to the membrane () probably because: (i) both PE and cholesterol have smaller hydrophilic head groups than that of phosphatidylcholine (PC) and (ii) cholesterol has a much bulkier hydrophobic structure than that of PC. The small size of hydrophilic head group of phospholipids probably helps the penetration of the hydrophobic residues (M173, F234, V304, and I367) in the Ca2+‐binding loops of the Syt1C2A/B domain into the phospholipid bilayer upon Ca2+‐dependent binding.
Figure 13. Figure 13. Regulation of the SNARE complex formation by lipids. (A) Sphingosine exposes the SNARE motif of synaptobrevin 2 (Syb2) from the synaptic vesicular membrane (), while arachidonic acid releases the Habc domain from the SNARE motif of syntaxin 1A (Synt1A) (). Both sphingosine and arachidonic acid are capable of promoting the formation of SNARE complex, and subsequent synaptic vesicle exocytosis. (B) Chemical structures of sphingosine and arachidonic acid. Both lipids have chemical properties of detergents.


Figure 1. Synaptic vesicle proteins that are involved in regulating Ca2+‐triggered exocytotic processes. The domain structures of synaptic vesicle proteins, which are involved in Ca2+‐triggered exocytotic processes, are illustrated with a brief description of their major functions. The number in parentheses is the average copy number of protein per synaptic vesicle (). Syt1, synaptotagmin 1; SV2, synaptic vesicle protein 2; SCAMP, secretory carrier membrane protein; Syb2, synaptobrevin 2 (also known as VAMP2); CSPα, cysteine string protein α; CaMKs, Ca2+/calmodulin‐dependent protein kinases; GAP, GTPase‐activating protein; GEF, guanine nucleotide exchange factor; PS, phosphatidylserine; PI, phosphatidylinositol; PIP2, phosphatidylinositol 4,5‐bisphosphate. Synapsin interacts with the acidic synaptic vesicle membrane in a phosphorylation/dephosphorylation‐dependent manner (), while rab3a is associated with synaptic vesicles in a GTP‐dependent manner (). The transmembrane region of Syb2 is associated with synaptophysin in the presence of cholesterol ().


Figure 2. Ca2+‐tiggered exocytosis regulated by synaptotagmin 1 (Syt1). (A) Synaptotagmin 1 (Syt1) interacts with the target membrane by electrostatic and van der Waals interactions in a Ca2+‐dependent manner to mediate exocytosis (). The R233 residue of the Syt1C2A domain and the K326, K327, R398, and R399 residues of the Syt1C2B domain are identified as critical residues for electrostatic interaction with membranes for the Syt1 function (). The M173, F234 residues of the Syt1C2A domain and the V304 and I367 residues of the Syt1C2B domain penetrate into the membrane and form van der Waals interaction with hydrophobic lipids of the membrane (). Syt1 also interacts with assembled SNARE complex composed of synaptobrevin 2 (Syb2), syntaxin 1 (Synt1), and SNAP25 (). The Ca2+‐dependent interaction among Syt1, SNARE complex, and membranes are important to mediate the synaptic vesicle exocytosis (), but the molecular mechanism of the interaction is not fully appreciated. (B) The domain structures of Syt1, Syb2, syntaxin 1A (Synt1A), SNAP25, and ferlins. SNAP25 is located in the plasma membrane, without transmembrane region, via palmitoylated C85, C88, C90, and C92 residues between the N‐terminal and C‐terminal SNARE motifs (). The N‐terminal Habc domain () of Synt1A is capable of interacting with the SNARE motif of Synt1A, which hinders the efficient formation of ternary SNARE complex composed of Synt1A, Syb2, and SNAP25. Otoferlin is involved in regulating the Ca2+‐triggered synaptic vesicle exocytosis at synapses of auditory hair cells, where presynaptic SNARE proteins such as Synt1, SNAP25, and Syb2 are not expressed (). However, unlike Syt1, the functions of otoferlin are not clearly demonstrated. Dysferlin, an isoform of otoferlin, regulates Ca2+‐dependent sarcolemma resealing which is mediated by an exocytotic process (). Both otoferlin and dysferlin are probably involved in mediating Ca2+‐triggered exocytotic process by a similar mechanism, which is different from that of Syt1.


Figure 3. Mechanisms of the Ca2+‐dependent synaptotagmin 1 (Syt1) C2 domain binding to the membrane. (A) The Ca2+‐binding loops of the Syt1C2A and Syt1C2B domains. Aspartate (D) residues that directly interact with Ca2+ are indicated by red color, R233 residue that interacts with acidic head groups of phospholipids in the membrane is indicated by white color, and hydrophobic residues that penetrate into the phospholipid bilayer are indicated by blue color. (B) The hydrophobic residues of the synaptotagmin (Syt) C2A and C2B domains, which directly penetrate into the membrane and form van der Waals interaction with hydrophobic lipids. The Ca2+ affinities of the isolated C2 domains were measured in the presence of acidic‐liposomes reconstituted with 75% phosphatidylcholine (PC) and 25% phosphatidylserine (PS) (). (C) The Ca2+ affinities and total amount of the wild‐type and mutant forms of Syt1C2A/B domain binding to synaptic‐liposomes (41% phosphatidylcholine, 32% phosphatidylethanolamine, 12% phosphatidylserine, 5% phosphatidylinositol, and 10% cholesterol) containing 0.25% phosphatidylinositol phosphate (PIP) and 0.05% phosphatidylinositol 4,5‐bisphosphate (PIP2) (). The number in parentheses is an EC50 value of Ca2+ concentration for the Syt1 cytosolic fraction binding to synaptic‐liposomes containing 0.5% PIP and 0.1% PIP2 ().


Figure 4. Regulation of the interaction between synaptotagmin 1 (Syt1) and the membrane by acidic‐phospholipids. (A) Acidic phospholipids such as phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylinositol phosphate (PIP), and phosphatidylinositol 4,5‐bisphosphate (PIP2) are essential for the efficient Ca2+ binding to the C2 domains of synaptotagmin 1 (Syt1). The R233 residue of the Syt1C2A domain, and the K326 and K327 residues of the Syt1C2B domain are important for the efficient Syt1 binding to the membrane in a Ca2+‐dependent manner (). In addition, the R398 and R399 residues of the Syt1C2B domain are essential for the Syt1 function that mediates Ca2+‐triggered exocytosis (). These basic residues interact with acidic head groups of phospholipids in the membrane. Neurons increase PIP, PIP2, and inositol hexakisphosphate (IP6) concentrations by multiple action potential‐stimulations. IP6, a PIP2 metabolite inhibits the function of Syt1 by interacting with the Ca2+‐binding loops of the Syt1C2B domain (). DAG, diacylglycerol. (B) The hydrophilic head groups of PI, PS, and PIP2. The Ca2+ affinity of Syt1 for the membrane binding depends on the acidity of the membrane (). Therefore, PIP2 is much better than PI and PS for the Ca2+‐dependent Syt1 binding to the membrane. Even though the net acidities are the same between PS and PI, PS is better than PI for the Ca2+‐dependent Syt1 binding to the membrane ().


Figure 5. The mechanisms of synaptic vesicle docking, which are mediated by synaptobrevin 2 (Syb2) and synaptotagmin 1 (Syt1). Synaptobrevin 2 (Syb2) is capable of interacting with syntaxin 1 (Synt1)/SNAP25 duplex (), and the basic residues of the Syt1C2B domain are also capable of interacting with either PIP2 in the plasma membrane or Synt1/SNAP25 duplex (). These Ca2+‐independent interactions lead to the synaptic vesicle docking and priming to the target plasma membrane. The primed synaptic vesicles are ready for Ca2+‐triggered exocytosis by extracellular Ca2+ influx after action potential‐stimulations. Neurons lacking Syb2 showed about tenfold decrease in the size of readily releasable pool (RRP), which is affected by the synaptic vesicle priming and docking (). However, neurons expressing Syt1K326A,K327A did not alter the RRP size compared to that of neurons expressing wild‐type Syt1 (). Therefore, the role of the Syt1C2B domain in mediating synaptic vesicle docking and priming is not universally accepted.


Figure 6. Different modes of neurotransmitter release at presynaptic terminals. Three different modes of neurotransmitter release are illustrated (). Action potentials trigger extracellular Ca2+ influx into the presynaptic terminals, and neurotransmitters are released by synchronous or asynchronous modes. Neurons also spontaneously release neurotransmitters without action potentials, but mainly in a Ca2+‐dependent manner (). Ca2+ from either intracellular storages or local Ca2+ channel opening triggers spontaneous mini release. PIP2, phosphatidylinositol 4,5‐bisphosphate; DAG, diacylglycerol; IP3, inositol 1,4,5‐triphosphate; Syt, synaptotagmin; Doc2, double C2 protein; Syb, synaptobrevin (also known as vesicle‐associated membrane protein, VAMP); Vti1a, Vps10p‐tail‐interactor‐1a.


Figure 7. Comparison of amino acid sequences of the synaptotagmin 7 C2A/B (Syt7C2A/B) domains from zebrafish, mouse, rat, and human. Amino acid sequences of the Syt7C2A/B domains from zebrafish (genebank accession # NM_001245957), mouse (genebank accession # NM_173068), rat (genebank accession # NM_021659), and human (genebank accession # NM_004200). The residues that are not conserved in zebrafish are indicated by yellow color. Conserved residues among different species are indicated by grey boxes, and identical residues are not shown. Aspartate residues that directly interact with Ca2+ are indicated by red color.


Figure 8. Domain structures of the synaptic vesicle proteins that have four transmembrane regions. (A) Synaptophysin, synaptogyrin, and secretory carrier membrane protein (SCAMP) have four transmembrane regions. Synaptophysin has four isoforms—synaptophysin 1, synaptophysin 2 (also known as synaptoporin), pantophysin, and mitsugumin 29. Synaptogyrin has three isoforms (synaptogyrin 1‐3), and SCAMP has five isoforms (SCAMP 1‐5). NGly, N‐glycosylation site; Syb2, synaptobrevin 2; Synt1, syntaxin 1; PIP2, phosphatidylinositol 4,5‐bisphosphate; Syt, synaptotagmin; [P]n, multiple phosphorylation sites. (B) Synaptophysin 1 is capable of interacting with either dynamin or Syb2 (), while SCAMP1 is capable of interacting with intersectin1 and γ‐synergin (). Intersectin 1 and γ‐synergin are involved in the endocytotic process in the plasma membrane and vesicle formation in the trans‐Golgi complex, respectively. Therefore, the main function of these proteins in exocytotic processes is probably the generation of releasable synaptic vesicles, which is important for the synaptic facilitation and long‐term potentiation (LTP).


Figure 9. Domain structure of synapsin and its proposed mechanism of synaptic vesicle mobilization. (A) Conserved domains among synapsin isoforms. Phosphorylation sites of synapsin 1a are indicated by “P” in the circle. In particular, the phosphorylation sites by Ca2+/calmodulin‐dependent protein kinases (CaMKs) are indicated by red circles. The “A” domain is capable of interacting with the acidic synaptic vesicle membrane, but phosphorylation of serine9 residue in the “A” domain triggers the dissociation of synapsin from synaptic vesicles. The “C” domain is capable of interacting with the synaptic vesicle membrane and actin filaments, while the “D” domain can interact with SH3‐proteins. Both “C” and “E” domains are involved in synapsin oligomerization. (B) The proposed mechanism of synaptic vesicle mobilization by synapsin 1a and CaMKs (). Repeated stimulations of neurons increase the intracellular Ca2+ concentration, and subsequently activate CaMKs in presynaptic terminals. Activated CaMKs phosphorylate synapsin 1a, and phosphorylated synapsins are dissociated from the cluster composed of synaptic vesicles, synapsin, and actin filaments. This mobilizes synaptic vesicles for exocytosis from the synapsin/CaMK‐responsive synaptic vesicle pools.


Figure 10. Domain structure of cysteine string protein (CSP) and its function in synaptic vesicle trafficking. (A) The domain structure of CSP isoforms. CSPα is capable of interacting with various types of proteins such as synaptotagmin 1 (Syt1), the C2A domain of synaptotagmin 9 (Syt9C2A), SNAP25, syntaxin (Synt), synaptobrevin 2 (Syb2), small glutamine‐rich TPR protein (SGT), GTP‐binding protein (Gαβγ), and N‐type Ca2+ channel. PKA, protein kinase A; PKB, protein kinase B; HIP14, huntingtin‐interacting protein 14. (B) The major function of CSPα, as a component of the chaperone complex composed of Hsc70 and SGT, is the maintenance of the expression levels of SNAP25 and dynamin 1 (). Both SNAP25 and dynamin 1 play critical roles in synaptic vesicle exocytosis and endocytosis.


Figure 11. Mechanism of the rab3‐mediated synaptic vesicle priming to the active zone in the plasma membrane. Rab3a, rab3b, rab3c, and rab27b are expressed in synaptic vesicles (). GTP‐bound form of rab3/rab27b interacts with both RIM and Munc13 proteins (). RIM protein is a component of the presynaptic active zone protein complex (). Munc13 is located in presynaptic active zone and binds to plasma membrane in a Ca2+/diacylglycerol (DAG)‐dependent manner (). Solid line between proteins represents an interaction. Munc13 also stimulates the SNARE complex formation that mediates exocytosis. RIM‐BP, RIM‐binding protein; DAG, diacylglycerol; PIP2, phosphatidylinositol 4,5‐bisphosphate.


Figure 12. The effects of cholesterol and phosphatidylethanolamine (PE) on the Ca2+‐dependent synaptotagmin 1 (Syt1)‐binding to the membrane. Phosphatidylethanolamine (PE) and cholesterol enhanced the Ca2+‐dependent Syt1C2A/B domain binding to the membrane () probably because: (i) both PE and cholesterol have smaller hydrophilic head groups than that of phosphatidylcholine (PC) and (ii) cholesterol has a much bulkier hydrophobic structure than that of PC. The small size of hydrophilic head group of phospholipids probably helps the penetration of the hydrophobic residues (M173, F234, V304, and I367) in the Ca2+‐binding loops of the Syt1C2A/B domain into the phospholipid bilayer upon Ca2+‐dependent binding.


Figure 13. Regulation of the SNARE complex formation by lipids. (A) Sphingosine exposes the SNARE motif of synaptobrevin 2 (Syb2) from the synaptic vesicular membrane (), while arachidonic acid releases the Habc domain from the SNARE motif of syntaxin 1A (Synt1A) (). Both sphingosine and arachidonic acid are capable of promoting the formation of SNARE complex, and subsequent synaptic vesicle exocytosis. (B) Chemical structures of sphingosine and arachidonic acid. Both lipids have chemical properties of detergents.
 1.Abraham C, Bai L, Leube RE. Synaptogyrin‐dependent modulation of synaptic neurotransmission in Caenorhabditis elegans. Neuroscience 190: 75–88, 2011.
 2.Antonin W, Riedel D, von Mollard GF. The SNARE Vti1a‐β is localized to small synaptic vesicles and participates in a novel SNARE complex. J Neurosci 20: 5724–5732, 2000.
 3.Bai J, Tucker WC, Chapman ER. PIP2 increases the speed of response of synaptotagmin and steers its membrane‐penetration activity toward the plasma membrane. Nat Struct Mol Biol 11: 36–44, 2004.
 4.Balch WE. Small GTP‐binding proteins in vesicular transport. Trends Biochem Sci 15: 473–477, 1990.
 5.Bansal D, Miyake K, Vogel SS, Groh S, Chen CC, Williamson R, McNeil PL, Campbell KP. Defective membrane repair in dysferlin‐deficient muscular dystrophy. Nature 423: 168–172, 2003.
 6.Baumert M, Maycox PR, Navone F, De Camilli P, Jahn R. Synaptobrevin: An integral membrane protein of 18,000 daltons present in small synaptic vesicles of rat brain. EMBO J 8: 379–384, 1989.
 7.Becher A, Drenckhahn A, Pahner I, Margittai M, Jahn R, Ahnert‐Hilger G. The synaptophysin‐synaptobrevin complex: A hallmark of synaptic vesicle maturation. J Neurosci 19: 1922–1931, 1999.
 8.Benfenati F, Greengard P, Brunner J, Bähler M. Electrostatic and hydrophobic interactions of synapsin I and synapsin I fragments with phospholipid bilayers. J Cell Biol 108, 1851–1862, 1989.
 9.Best AR, Regehr WR. Inhibitory regulation of electrically coupled neurons in the inferior olive is mediated by asynchronous release of GABA. Neuron 62: 555–565, 2009.
 10.Beurg M, Michalski N, Safieddine S, Bouleau Y, Schneggenburger R, Chapman ER, Petit C, Dulon D. Control of exocytosis by synaptotagmins and otoferlin in auditory hair cells. J Neurosci 30: 13281–13290, 2010.
 11.Boal F, Zhang H, Tessier C, Scotti P, Lang J. The variable C‐terminus of cysteine string proteins modulates exocytosis and protein‐protein interactions. Biochemistry 43: 16212–16223, 2004.
 12.Boal F, Le Pevelen S, Cziepluch C, Scotti P, Lang J. Cysteine‐string protein isoform beta (Cspbeta) is targeted to the trans‐Golgi network as a non‐palmitoylated CSP in clonal β‐cells. Biochim Biophys Acta 1773: 109‐119, 2007.
 13.Boal F, Laguerre M, Milochau A, Lang J, Scotti PA. A charged prominence in the linker domain of the cysteine‐string protein Cspα mediates its regulated interaction with the calcium sensor synaptotagmin 9 during exocytosis. FASEB J 25: 132–143, 2011.
 14.Bonanomi D, Rusconi L, Colombo CA, Benfenati F, Valtorta F. Synaptophysin I selectively specifies the exocytic pathway of synaptobrevin 2/VAMP2. Biochem J 404: 525–534, 2007.
 15.Brand SH, Laurie SM, Mixon MB, Castle JD. Secretory carrier membrane proteins 31‐35 define a common protein composition among secretory carrier membranes. J Biol Chem 266: 18949–18957, 1991.
 16.Brand SH , Castle JD. SCAMP 37, a new marker within the general cell surface recycling system. EMBO J 12: 3753–3761, 1993.
 17.Bronk P, Wenniger JJ, Dawson‐Scully K, Guo X, Hong S, Atwood HL, Zinsmaier KE. Drosophila Hsc70‐4 is critical for neurotransmitter exocytosis in vivo. Neuron 30: 475–488, 2001.
 18.Brose N, Hofmann K, Hata Y, Südhof TC. Mammalian homologues of Caenorhabditis elegans unc‐13 gene define novel family of C2‐domain proteins. J Biol Chem 270: 25273–252880, 1995.
 19.Cao P, Maximov A, Südhof TC. Activity‐dependent IGF‐1 exocytosis is controlled by the Ca2+‐sensor synaptotagmin‐10. Cell 145: 300–311, 2011.
 20.Cao P, Yang X, Südhof TC. Complexin activates exocytosis of distinct secretory vesicles controlled by different synaptotagmins. J Neurosci 33: 1714–1727, 2013.
 21.Castillo PE, Janz R, Südhof TC, Tzounopoulos T, Malenka RC, Nicoll RA. Rab3A is essential for mossy fibre long‐term potentiation in the hippocampus. Nature 388: 590–593, 1997.
 22.Chamberlain LH, Burgoyne RD. Cysteine string protein functions directly in regulated exocytosis. Mol Biol Cell 9: 2259–2267, 1998.
 23.Chamberlain LH, Burgoyne RD. Cysteine‐string protein: The chaperone at synapses. J Neurochem 74: 1781–1789, 2000.
 24.Chang WP, Südhof TC. SV2 renders primed synaptic vesicles competent for Ca2+‐induced exocytosis. J Neurosci 29: 883–897, 2009.
 25.Chapman ER, Hanson PI, An S, Jahn R. Ca2+ regulates the interaction between synaptotagmin and syntaxin 1. J Biol Chem 270: 23667–23671, 1995.
 26.Chapman ER, Davis AF. Direct interaction of a Ca2+‐binding loop of synaptotagmin with lipid bilayers. J Biol Chem 273: 13995–14001, 1998.
 27.Chappie JS, Dyda F. Building a fission machine – structural insights into dynamin assembly and activation. J Cell Sci 126: 2773–2784, 2013.
 28.Chardin P. The ras superfamily proteins. Biochimie 70: 865–868, 1988.
 29.Cheetham JJ, Hilfiker S, Benfenati F, Weber T, Greengard P, Czernik AJ. Identification of synapsin I peptides that insert into lipid membranes. Biochem J 354: 57–66, 2001.
 30.Cherfils J, Zeghouf M. Regulation of small GTPases by GEFs, GAPs, and GDIs. Physiol Rev 93: 269–309, 2013.
 31.Cho W, Stahelin. Membrane binding and subcellular targeting of C2 domains. Biochim Biophys Acta 1761, 838–849, 2006.
 32.Cingolani LA, Goda Y. Actin in action: The interplay between the actin cytoskeleton and synaptic efficacy. Nat Rev Neurosci 9: 344–356, 2008.
 33.Connell E, Darios F, Broersen K, Gatsby N, Peak‐Chew SY, Rickman C, Davletov B. Mechanism of arachidonic acid action on syntaxin‐Munc18. EMBO Rep 8: 414–419, 2007.
 34.Conti R, Tan YP, Llano I. Action potential‐evoked and ryanodine‐sensitive spontaneous Ca2+ transients at the presynaptic terminal of a developing CNS inhibitory synapse. J Neurosci 24: 6946–6957, 2004.
 35.Cooper AP, Gillespie DC. Synaptotagmin I and II in the developing rat auditory brainstem: Synaptotagmin I is transiently expressed in glutamate‐releasing immature inhibitory terminals. J Comp Neurol 519: 2417–2433, 2011.
 36.Crowder KM, Gunther JM, Jones TA, Hale BD, Zhang HZ, Peterson MR, Scheller RH, Chavkin C, Bajjalieh SM. Abnormal neurotransmission in mice lacking synaptic vesicle protein 2A (SV2A). Proc Natl Acad Sci U S A 96: 15268–15273, 1999.
 37.Dai H, Shin OH, Machius M, Tomchick DR, Südhof TC, Rizo J. Structural basis for the evolutionary inactivation of Ca2+ binding to synaptotagmin 4. Nat Struct Mol Biol 11: 844–849, 2004.
 38.Daly C, Ziff EB. Ca2+‐dependent formation of a dynamin‐synaptophysin complex: Potential role in synaptic vesicle endocytosis. J Biol Chem 277: 9010–9015, 2002.
 39.Darios F, Davletov B. Omega‐3 and omega‐6 fatty acids stimulate cell membrane expansion by acting on syntaxin 3. Nature 440: 813–817, 2006.
 40.Darios F, Connell E, Davletov B. Phospholipases and fatty acid signalling in exocytosis. J Physiol 585: 699–704, 2007.
 41.Darios F, Wasser C, Shakirzyanova A, Giniatullin A, Goodman K, Munoz‐Bravo JL, Raingo J, Jorgacevski J, Kreft M, Zorec R, Rosa JM, Gandia L, Gutiérrez LM, Binz T, Giniatullin R, Kavalali ET, Davletov B. Sphingosine facilitates SNARE complex assembly and activates synaptic vesicle exocytosis. Neuron 62: 683–694, 2009.
 42.Davletov BA, Südhof TC. A single C2 domain from synaptotagmin I is sufficient for high affinity Ca2+/phospholipid binding. J Biol Chem 268: 26386–26390, 1993.
 43.Daw MI, Tricoire L, Erdelyi F, Szabo G, McBain CJ. Asynchronous transmitter release from cholecystokinin‐containing inhibitory interneurons is widespread and target‐cell independent. J Neurosci 29: 11112–11122, 2009.
 44.Dawson‐Scully K, Bronk P, Atwood HL, Zinsmaier KE. Cysteine‐string protein increases the calcium sensitivity of neurotransmitter exocytosis in Drosophila. J Neurosci 20: 6039–6047, 2000.
 45.Deák F, Schoch S, Liu X, Südhof TC, Kavalali ET. Synaptobrevin is essential for fast synaptic vesicle endocytosis. Nat Cell Biol 6: 1102–1108, 2004.
 46.Deák F, Shin OH, Kavalali ET, Südhof TC. Structural determinants of synaptobrevin 2 function in synaptic vesicle fusion. J Neurosci 26: 6668–6676, 2006.
 47.Dean C, Liu H, Dunning FM, Chang PY, Jackson MB, Chapman ER. Synaptotagmin‐IV modulates synaptic function and long‐term potentiation by regulating BDNF release. Nat Neurosci 12:767–776, 2009.
 48.Dean C, Liu H, Staudt T, Stahlberg MA, Vingill S, Bückers J, Kamin D, Engelhardt J, Jackson MB, Hell SW, Chapman ER. Distinct subsets of Syt‐IV/BDNF vesicles are sorted to axons versus dendrites and recruited to synapses by activity. J Neurosci 32: 5398–5413, 2012.
 49.De Camilli P, Takei K, McPherson PS. The function of dynamin in endocytosis. Curr Opin Neurobiol 5: 559–565, 1995.
 50.Doussau F, Clabecq A, Henry JP, Darchen F, Poulain B. Calcium‐dependent regulation of rab3 in short‐term plasticity. J Neurosci 18: 3147–3157, 1998.
 51.Dulubova I, Lou X, Lu J, Huryeva I, Alam A, Schneggenburger R, Südhof TC, Rizo J. A Munc13/RIM/Rab3 tripartite complex: From priming to plasticity? EMBO J 24: 2839–2850, 2005.
 52.Duncan CJ. Role of calcium in triggering the release of transmitters at the neuromuscular junction. Cell Calcium 4: 171–193, 1983.
 53.Eberhard DA, Holz RW. Calcium promotes the accumulation of polyphosphoinositides in intact and permeabilized bovine adrenal Chromaffin cells. Cell Mol Neurobiol 11: 357–370, 1991.
 54.Edelmann L, Hanson PI, Chapman ER, Jahn R. Synaptobrevin binding to synaptophysin: A potential mechanism for controlling the exocytotic fusion machine. EMBO J 14: 224–231, 1995.
 55.Eiden LE, Schäfer MK, Weihe E, Schütz B. The vesicular amine transporter family (SLC18): Amine/protein antiporters required for vesicular accumulation and regulated exocytotic secretion of monoamines and acetylcholine. Pflugers Arch 447:636–640, 2004.
 56.El Far O, Seagar M. A role for V‐ATPase subunits in synaptic vesicle fusion? J Neurochem 117:603–612, 2011.
 57.Esser L, Wang CR, Hosaka M, Smagula CS, Südhof TC, Deisenhofer J. Synapsin I is structurally similar to ATP‐utilizing enzymes. EMBO J 17: 977–984, 1998.
 58.Evans GJ, Wilkinson MC, Graham ME, Turner KM, Chamberlain LH, Burgoyne RD, Morgan A. Phosphorylation of cysteine string protein by protein kinase A. Implications for the modulation of exocytosis. J Biol Chem 276: 47877–47885, 2001.
 59.Evans GJ, Morgan A Phosphorylation‐dependent interaction of synaptic vesicle proteins cysteine string protein and synaptotagmin I. Biochem J 364: 343–347, 2002.
 60.Evans GJ, Morgan A, Burgoyne RD. Tying everything together: The multiple roles of cysteine string protein (CSP) in regulated exocytosis. Traffic 4: 653–659, 2003.
 61.Evans GJO, Cousin MA. Tyrosine phosphorylation of synaptophysin in synaptic vesicle recycling. Biochem Soc Trans 33: 1350–1353, 2005.
 62.Evans GJ, Barclay JW, Prescott GR, Jo SR, Burgoyne RD, Birnbaum MJ, Morgan A. Protein kinase B/Akt is a novel cysteine string protein kinase that regulates exocytosis release kinetics and quantal size. J Biol Chem 281: 1564–1572, 2006.
 63.Feany MB, Lee S, Edwards RH, Buckley KM. The synaptic vesicle protein SV2 is a novel type of transmembrane transporter. Cell 70: 861–867, 1992.
 64.Fei H, Grygoruk A, Brooks ES, Chen A, Krantz DE. Trafficking of vesicular neurotransmitter transporters. Traffic 9: 1425–1436, 2008.
 65.Fernandez I, Ubach J, Dulubova I, Zhang X, Südhof TC, Rizo J. Three‐dimensional structure of an evolutionarily conserved N‐terminal domain of syntaxin 1A. Cell 94: 841–849, 1998.
 66.Fernandez I, Araç D, Ubach J, Gerber SH, Shin O, Gao Y, Anderson RG, Südhof TC, Rizo J. Three‐dimensional structure of the synaptotagmin 1 C2B‐domain: Synaptotagmin 1 as a phospholipid binding machine. Neuron 32:1057–1069, 2001.
 67.Fernández‐Chacón R, Alvarez de Toledo G, Hammer RE, Südhof TC. Analysis of SCAMP1 function in secretory vesicle exocytosis by means of gene targeting in mice. J Biol Chem 274: 32551–32554, 1999.
 68.Fernández‐Chacón R, Südhof TC. Novel SCAMPs lacking NPF repeats: Ubiquitous and synaptic vesicle‐specific forms implicate SCAMPs in multiple membrane trafficking functions. J Neurosci 20: 7941–7950‐49, 2000.
 69.Fernández‐Chacón R, Achiriloaie M, Janz R, Albanesi JP, Südhof TC. SCAMP1 function in endocytosis. J Biol Chem 275: 12752–12756, 2000.
 70.Fernández‐Chacón R, Königstorfer A, Gerber SH, García J, Matos MF, Stevens CF, Brose N, Rizo J, Rosenmund C, Südhof TC. Synaptotagmin I functions as a calcium regulator of release probability. Nature 410: 41–49, 2001.
 71.Fernández‐Chacón R, Wölfel M, Nishimune H, Tabares L, Schmitz F, Castellano‐Munoz M, Rosenmund C, Montesinos ML, Sanes JR, Scheggemburger R, Südhof TC. The synaptic vesicle protein CSP alpha prevents presynaptic degeneration. Neuron 42: 237–251, 2004.
 72.Fischer von Mollard G, Südhof TC, Jahn R. A small GTP‐binding protein dissociates from synaptic vesicles during exocytosis. Nature 349: 79–81, 1991.
 73.Fornasiero EF, Raimondi A, Guarnieri FC, Orlando M, Fesce R, Benfenati F, Valtorta F. Synapsins contribute to the dynamic spatial organization of synaptic vesicles in an activity‐dependent manner. J Neurosci 32: 12214–12227, 2012.
 74.Fox MA, Sanes JR. Synaptotagmin I and II are present in distinct subsets of central synapses. J Comp Neurol 503: 280–296, 2007.
 75.Fukuda M, Kojima T, Aruga J, Niinobe M, Mikoshiba K. Functional diversity of C2 domains of synaptotagmin family. Mutational analysis of inositol high polyphosphate binding domain. J Biol Chem 270: 26523–26527, 1995.
 76.Fukuda M. Synaptotagmin‐like protein (Slp) homology domain 1 of Slac2‐a/melanophilin is a critical determinant of GTP‐dependent specific binding to Rab27A. J Biol Chem 277: 40118–40124, 2002.
 77.Fukuda M, Kowalchyk JA, Zhang X, Martin TF, Mikoshiba K. Synaptotagmin IX regulates Ca2+‐dependent secretion in PC12 cells. J Biol Chem 277: 4601–4604, 2002.
 78.Fukuda M. Distinct Rab binding specificity of Rim1, Rim2, rabphilin, and Noc2. Identification of a critical determinant of Rab3A/Rab27A recognition by Rim2. J Biol Chem 278: 15373–15380, 2003.
 79.Fukuda M, Kanno E, Satoh M, Saegusa C, Yamamoto A. Synaptotagmin VII is targeted to dense‐core vesicles and regulates their Ca2+‐dependent exocytosis in PC12 cells. J Biol Chem 279: 52677–52684, 2004.
 80.Fukuda M. Rab27 and its effectors in secretory granule exocytosis: A novel docking machinery composed of a Rab27 effector complex. Biochem Soc Trans 34: 691–695, 2006.
 81.Fykse EM, Takei K, Walch‐Solimena C, Geppert M, Jahn R, De Camilli P, Südhof TC. Relative properties and localizations of synaptic vesicle protein isoforms: The case of the synaptophysins. J Neurosci 13: 4997–5007, 1993.
 82.Geppert M, Archer BT III, Südhof TC. Synaptotagmin II. A novel differentially distributed form of synaptotagmin. J Biol Chem 266: 13548–13552, 1991.
 83.Geppert M, Goda Y, Hammer RE, Li C, Rosahl TW, Stevens CF, Südhof TC. Synaptotagmin I: A major Ca2+ sensor for transmitter release at a central synapse. Cell 79: 717–727, 1994.
 84.Giraudo CG, Eng WS, Melia TJ, Rothman JE. A clamping mechanism involved in SNARE‐dependent exocytosis. Science 313: 676–680, 2006.
 85.Glitsch MD. Spontaneous neurotransmitter release and Ca2+ ‐ how spontaneous is spontaneous neurotransmitter release? Cell Calcium 43: 9–15, 2008.
 86.Gordon SL, Leube RE, Cousin MA. Synaptophysin is required for synaptobrevin retrieval during synaptic vesicle endocytosis. J Neurosci 31: 14032–14036, 2011.
 87.Gorleku OA, Chamberlain LH. Palmitoylation and testis‐enriched expression of the cysteine‐string protein beta isoform. Biochemistry 49: 5308–5313, 2010.
 88.Granseth B, Odermatt B, Royle SJ, Lagnado L. Clathrin‐mediated endocytosis: The physiological mechanism of vesicle retrieval at hippocampal synapses. J Physiol 585: 681–686, 2007.
 89.Groffen AJ, Martens S, Díez Arazola R, Cornelisse LN, Lozovaya N, de Jong AP, Goriounova NA, Habets RL, Takai Y, Borst JG, Brose N, McMahon HT, Verhage M. Doc2b is a high‐affinity Ca2+ sensor for spontaneous neurotransmitter release. Science 327: 1614–1618, 2010.
 90.Grønborg M, Pavlos NJ, Brunk I, Chua JJE, Münster‐Wandowski A, Riedel D, Ahnert‐Hilger G, Urlaub H, Jahn R. Quantitative comparison of glutamatergic and GABAergic synaptic vesicles unveils selectivity for few proteins including MAL2, a novel synaptic vesicle protein. J Neurosci 30: 2–12, 2010.
 91.Guo Z, Liu L, Cafiso D, Castle D. Perturbation of a very late step of regulated exocytosis by a secretory carrier membrane protein (SCAMP2)‐derived peptide. J Biol Chem 277: 35357–35363, 2002.
 92.Haass NK, Kartenbeck MA, Leube RE. Pantophysin is a ubiquitously expressed synaptophysin homologue and defines constitutive transport vesicles. J Cell Biol 134: 731–746, 1996.
 93.Han C, Chen T, Yang M, Li N, Liu H, Cao X. Human SCAMP5, a novel secretory carrier membrane protein, facilitates calcium‐triggered cytokine secretion by interaction with SNARE machinery. J Immunol 182: 2986–2996, 2009.
 94.Hashimoto T, Ishii T, Ohmori H. Release of Ca2+ is the crucial step for the potentiation of IPSCs in the cultured cerebellar Purkinje cells of the rat. J Physiol 497: 611–627, 1996.
 95.Hefft S, Jonas P. Asynchronous GABA release generates long‐lasting inhibition at a hippocampal interneuron‐principal neuron synapse. Nat Neurosci 8: 1319–1328, 2005.
 96.Hosaka M, Südhof TC. Synapsins I and II are ATP‐binding proteins with differential Ca2+ regulation. J Biol Chem 273: 1425–1429, 1998.
 97.Hosaka M, Südhof TC. Synapsin III, a novel synapsin with an unusual regulation by Ca2+. J Biol Chem 273: 13371–13374, 1998.
 98.Hosaka M, Hammer RE, Südhof TC. A phosphor‐switch controls the dynamic association of synapsins with synaptic vesicles. Neuron 24: 377–387, 1999.
 99.Hu K, Carroll J, Fedorovich S, Rickman C, Sukhodub A, Davletov B. Vesicular restriction of synaptobrevin suggests a role for calcium in membrane fusion. Nature 415: 646–650, 2002.
 100.Hutagalung AH, Novick PJ. Role of Rab GTPase in membrane traffic and cell physiology. Physiol Rev 91: 119–149, 2011.
 101.Ishzuka T, Saisu H, Odani S, Abe T. Synaphin: A protein associated with the docking/fusion complex in presynaptic terminal. Biochem Biophys Res Commun 213: 1107–1114, 1995.
 102.Itoh T, Ishihara H, Shibasaki Y, Oka Y, Takenawa T. Autophosphorylation of type I phosphatidylinositol phosphate kinase regulates its lipid kinase activity. J Biol Chem 275: 19389–19394, 2000.
 103.Jahn R, Fasshauer D. Molecular machines governing exocytosis of synaptic vesicles. Nature 490: 201–207, 2012.
 104.Jahn R, Scheller RH. SNAREs – engines for membrane fusion. Nat Rev Mol Cell Biol 7: 631–643, 2006.
 105.Janz R, Südhof TC. Cellugyrin, a novel ubiquitous form of synaptogyrin that is phosphorylated by pp60c‐src. J Biol Chem 273: 2851–2857, 1998.
 106.Janz R, Südhof TC, Hammer RE, Unni V, Siegelbaum SA, Bolshakov VY. Essential roles in synaptic plasticity for synaptogyrin I and synaptophysin I. Neuron 24: 687–700, 1999.
 107.Janz R, Goda Y, Geppert M, Missler M, Südhof TC. SV2A and SV2B function as redundant Ca2+ regulators in neurotransmitter release. Neuron 24: 1003–1016, 1999.
 108.Johnson CP, Chapman ER. Otoferlin is a calcium sensor that directly regulates SNARE‐mediated membrane fusion. J Cell Biol 191: 187–197, 2010.
 109.Johnson SL, Franz C, Kuhn S, Furness DN, Rüttiger L, Münkner S, Rivolta MN, Seward EP, Herschman HR, Engel J, Knipper M, Marcotti W. Synaptotagmin IV determines the linear Ca2+ dependence of vesicle fusion at auditory ribbon synapses. Nat Neurosci 13: 45–52, 2010.
 110.Kaeser‐Woo YJ, Younts TJ, Yang X, Zhou P, Wu D, Castillo PE, Südhof TC. Synaptotagmin‐12 phosphorylation by cAMP‐dependent protein kinase is essential for hippocampal mossy fiber LTP. J Neurosci 33: 9769–9780, 2013.
 111.Kedra D, Pan HQ, Seroussi E, Fransson I, Guilbaud C, Collins JE, Dunham I, Blennow E, Roe BA, Piehl F, Dumanski JP. Characterization of the human synaptogyrin gene family. Hum Genet 103: 131–141, 1998.
 112.Kelly RB. Storage and release of neurotransmitters. Cell 72(Suppl): 43–53, 1993.
 113.Khvotchev MV, Südhof TC. Stimulus‐dependent dynamic homo‐ and heteromultimerization of synaptobrevin/VAMP and synaptophysin. Biochemistry 43: 15037–15043, 2004.
 114.Knaus P, Marquèze‐Pouey B, Scherer H, Betz H. Synaptoporin, a novel putative channel protein of synaptic vesicles. Neuron 5: 453–462, 1990.
 115.Kotake K, Ozaki N, Mizuta M, Sekiya S, Inagaki N, Seino S. Noc2, a putative zinc finger protein involved in exocytosis in endocrine cells. J Biol Chem 272: 29407–29410, 1997.
 116.Kweon DH, Kim CS, Shin YK. Regulation of neuronal SNARE assembly by the membrane. Nat Struct Biol 10: 440–447, 2003.
 117.Kwon SE, Chapman ER. Synaptophysin regulates the kinetics of synaptic vesicle endocytosis in central neurons. Neuron 70: 847–854, 2011.
 118.Lai AL, Huang H, Herrick DZ, Epp N, Cafiso DS. Synaptotagmin 1 and SNAREs form a complex that is structurally heterogeneous. J Mol Biol 405: 696–706, 2011.
 119.Lang T. SNARE proteins and ‘membrane rafts’. J Physiol 585: 693–698, 2007.
 120.Lazzell DR, Belizaire R, Thakur P, Sherry DM, Janz R. SV2B regulates synaptotagmin 1 by direct interaction. J Biol Chem 279: 52124–52131, 2004.
 121.Li JY, Jahn R, Dahlström A. Synaptotagmin I is present mainly in autonomic and sensory neurons of the rat peripheral nervous system. Neuroscience 63: 837–850, 1994.
 122.Li C, Ullrich B, Zhang JZ, Anderson RG, Brose N, Südhof TC. Ca2+‐dependent and ‐independent activities of neural and non‐neural synaptotagmins. Nature 375: 594–599, 1995.
 123.Li L, Shin OH, Rhee JS, Araç D, Rah JC, Rizo J, Südhof T, Rosenmund C. Phosphatidylinositol phosphates as co‐activators of Ca2+ binding to C2 domains of synaptotagmin 1. J Biol Chem 281: 15845–15852, 2006.
 124.Liao H, Ellena J, Liu L, Szabo G, Cafiso D, Castle D. Secretory carrier membrane protein SCAMP2 and phosphatidylinositol 4,5‐bisphosphate interactions in the regulation of dense core vesicle exocytosis. Biochemistry 46: 10909–10920, 2007.
 125.Liao H, Zhang J, Shestopal S, Szabo G, Castle A, Castle D. Nonredundant function of secretory carrier membrane protein isoforms in dense core vesicle exocytosis. Am J Physiol Cell Physiol 294: C797–C809, 2008.
 126.Lin RC, Scheller RH. Mechanisms of synaptic vesicle exocytosis. Annu Rev Cell Dev Biol 16: 19–49, 2000.
 127.Littleton JT, Stern M, Schulze K, Perin M, Bellen HJ. Mutational analysis of Drosophila synaptotagmin demonstrates its essential role in Ca2+‐activated neurotransmitter release. Cell 74: 1125–1134, 1993.
 128.Liu JP, Robinson PJ. Dynamin and endocytosis. Endocr Rev 16: 590–607, 1995.
 129.Liu L, Guo Z, Tieu Q, Castle A, Castle D. Role of secretory carrier membrane protein SCAMPs in granule exocytosis. Mol Biol Cell 13: 4266–4278, 2002.
 130.Liu Y, Sugiura Y, Lin W. The role of synaptobrevin1/VAMP1 in Ca2+‐triggered neurotransmitter release at the mouse neuromuscular junction. J Physiol 589: 1603–1618, 2011.
 131.Loewen CA, Lee SM, Shin YK, Reist NE. C2B polylysine motif of synaptotagmin facilitates a Ca2+‐independent stage of synaptic vesicle priming in vivo. Mol Biol Cell 17: 5211–5226, 2006.
 132.Lynch KL, Martin TF. Synaptotagmins I and IX function redundantly in regulated exocytosis but not endocytosis in PC12 cells. J Cell Sci 120: 617–627, 2007.
 133.Mackler JM, Drummond JA, Loewen CA, Robinson IM, Reist NE. The C2B Ca2+‐binding motif of synaptotagmin is required for synaptic transmission in vivo. Nature 418: 340–344, 2002.
 134.Magga JM, Jarvis SE, Arnot MI, Zamponi GW, Braun JE. Cysteine string protein regulates G protein modulation of N‐type calcium channels. Neuron 28: 195–204, 2000.
 135.Martin TF, Kowalchyk JA. Docked secretory vesicles undergoes Ca2+‐activated exocytosis in a cell‐free system. J Biol Chem 272: 14447–14453, 1997.
 136.Maximov A, Shin OH, Liu X, Südhof TC. Synaptotagmin‐12, a synaptic vesicle phosphoprotein that modulates spontaneous neurotransmitter release. J Cell Biol 176: 113–124, 2007.
 137.Maximov A, Lao Y, Li H, Chen X, Rizo J, Sørensen JB, Südhof TC. Genetic analysis of synaptotagmin‐7 function in synaptic vesicle exocytosis. Proc Natl Acad Sci U S A 105: 3986–3991, 2008.
 138.McMahon HT, Ushkaryov YA, Edelmann L, Link E, Binz T, Niemann H, Jahn R, Südhof TC. Cellubrevin is a ubiquitous tetanus‐toxin substrate homologous to a putative synaptic vesicle fusion protein. Nature 364: 346–349, 1993.
 139.McMahon HT, Missler M, Li C, Südhof TC. Complexins: Cytosolic proteins that regulate SNAP receptor function. Cell 83: 111–119, 1995.
 140.McMahon HT, Bolshakv VY, Janz R, Hammer RE, Siegelbaum SA, Südhof TC. Synaptophysin, a major synaptic vesicle protein, is not essential for neurotransmitter release. Proc Natl Acad Sci U S A 93: 4760–4764, 1996.
 141.Mercer AJ, Szalewski RJ, Jackman SL, Van Hook MJ, Thoreson WB. Regulation of presynaptic strength by controlling Ca2+ channel mobility: Effects of cholesterol depletion on release at the cone ribbon synapse. J Neurophysiol 107: 3468–3478, 2012.
 142.Miller LC, Swayne LA, Kay JG, Feng ZP, Jarvis SE, Zamponi GW, Braun JE. Molecular determinants of cysteine string protein modulation on N‐type calcium channels. J Cell Sci 116: 2967–2974, 2003.
 143.Min SW, Chang WP, Südhof TC. E‐Syts, a family of membraneous Ca2+‐sensor proteins with multiple C2 domains. Proc Natl Acad Sci U S A 104: 3823–3828, 2007.
 144.Mironov SL, Skorova EY. Stimulation of bursting in pre‐Bötzinger neurons by Epac through calcium release and modulation of TRPM4 and K‐ATP channels. J Neurochem 117: 295–308, 2011.
 145.Mitter D, Reisinger C, Hinz B, Hollmann S, Yelamanchili SV, Treiber‐Held S, Ohm TG, Herrmann A, Ahnert‐Hilger G. The synaptophysin/synaptobrevin interaction critically depends on the cholesterol content. J Neurochem 84: 35–42, 2003.
 146.Morgans CW, Kensel‐Hammes P, Hurley JB, Burton K, Idzerda R, McKnight GS, Bajjalieh SM. Loss of the synaptic vesicle protein SV2B results in reduced neurotransmission and altered synaptic vesicle protein expression in the retina. PLoS One 4: e5230, 2009.
 147.Moriyama Y, Maeda M, Futai M. The role of V‐ATPase in neuronal and endocrine systems. J Exp Biol 172: 171–178, 1992.
 148.Nagy A, Baker RR, Morris SJ, Whittaker VP. The preparation and characterization of synaptic vesicles of high purity. Brain Res 109: 285–309, 1976.
 149.Neumann S, Haverkamp S. Characterization of small‐field bistratified amacrine cells in macaque retina labeled by antibodies against synaptotagmin‐2. J Comp Neurol 521: 709–724, 2013.
 150.Ng EL, Tang BL. Rab GTPases and their roles in brain neurons and glia. Brain Res Rev 58: 236–246, 2008.
 151.Nishi M, Komazaki S, Kurebayashi N, Ogawa Y, Noda T, Lino M, Takeshima H. Abnormal features in skeletal muscle from mice lacking mitsugumin29. J Cell Biol 147: 1473–1480, 1999.
 152.Nishizuka Y. The molecular heterogeneity of protein kinase C and its implications for cellular regulation. Nature 334: 661–665, 1988.
 153.Nouvian R, Neef J, Bulankina AV, Reisinger E, Pangršič T, Frank T, Sikorra S, Brose N, Binz T, Moser T. Exocytosis at the hair cell ribbon synapse apparently operates without neuronal SNARE proteins. Nat Neurosci 14: 411–413, 2011.
 154.Nystuen AM, Schwendinger JK, Sachs AJ, Yang AW, Haider NB. A null mutation in VAMP1/synaptobrevin is associated with neurological defects and prewean mortality in the lethal‐wasting mouse mutant. Neurogenetics 8: 1–10, 2007.
 155.Ohyama T, Verstreken P, Ly CV, Rosenmund T, Rajan A, Tien AC, Haueter C, Schulze KL, Bellen HJ. Huntingtin‐interacting protein 14, a palmitoyl transferase required for exocytosis and targeting of CSP to synaptic vesicles. J Cell Biol 179: 1481–1496, 2007.
 156.Omote H, Miyaji T, Juge N, Moriyama Y. Vesicular neurotransmitter transporter: bioenergetics and regulation of glutamate transport. Biochemistry 50: 5558–5565, 2011.
 157.Pan Z, Yang D, Nagaraj RY, Nosek TA, Nishi M, Takeshima H, Cheng H, Ma J. Dysfunction of store‐operated calcium channel in muscle cells lacking mg29. Nat Cell Biol 4: 379–383, 2002.
 158.Pang ZP, Shin OH, Meyer AC, Rosenmund C, Südhof TC. A gain‐of‐function mutation in synaptotagmin‐1 reveals a critical role of Ca2+‐dependent soluble N‐ethylmaleimide‐sensitive factor attachment protein receptor complex binding in synaptic exocytosis. J Neurosci 26: 12556–12565, 2006.
 159.Pang ZP, Melicoff E, Padgett D, Liu Y, Teich AF, Dickey BF, Lin W, Adachi R, Südhof TC. Synaptotagmin‐2 is essential for survival and contributes to Ca2+ triggering of neurotransmitter release in central and neuromuscular synapses. J Neurosci 26:13493–13504, 2006.
 160.Pang ZP, Südhof TC. Cell biology of Ca2+‐triggered exocytosis. Curr Opin Cell Biol 22: 496–505, 2010.
 161.Pang ZP, Xu W, Cao P, Südhof TC. Calmodulin suppresses synaptotagmin‐2 transcription in cortical neurons. J Biol Chem 285: 33930–33939, 2010.
 162.Pang ZP, Bacaj T, Yang X, Zhou P, Xu W, Südhof TC. Doc2 supports spontaneous synaptic transmission by a Ca2+‐independent mechanism. Neuron 70: 244–251, 2011.
 163.Pangršič T, Lasarow L, Reuter K, Takago H, Schwander M, Riedel D, Frank T, Tarantino LM, Bailey JS, Strenzke N, Brose N, Müller U, Reisinger E, Moser T. Hearing requires otoferlin‐dependent efficient replenishment of synaptic vesicles in hair cells. Nat Neurosci 13: 869–876, 2010.
 164.Pangršič T, Reisinger E, Moser T. Otoferlin: A multi‐C2 domain protein essential for hearing. Trends Neurosci 35: 671–680, 2012.
 165.Park SJ, Itoh T, Takenawa T. Phosphatidylinositol 4‐phosphate 5‐kinase type I is regulated through phosphorylation response by extracellular stimuli. J Biol Chem 276: 4781–4787, 2001.
 166.Pavlos NJ, Jahn R. Distinct yet overlapping roles of Rab GTPases on synaptic vesicles. Small GTPases 2: 77–81, 2011.
 167.Pennuto M, Dunlap D, Contestabile A, Benfenati F, Valtorta F. Fluorescence resonance energy transfer detection of synaptophysin I and vesicle‐associated membrane protein 2 interactions during exocytosis from single live synapses. Mol Biol Cell 13: 2706–2717, 2002.
 168.Perin MS, Johnston PA, Ozcelik T, Jahn R, Francke U, Südhof TC. Structural and functional conservation of synaptotagmin (p65) in Drosophila and humans. J Biol Chem 266: 615–622, 1991.
 169.Perin MS, Brose N, Jahn R, Südhof TC. Domain structure of synaptotagmin (p65). J Biol Chem 266: 623–629, 1991.
 170.Prescott GR, Jenkins RE, Walsh CM, Morgan A. Phosphorylation of cysteine string protein on serine 10 triggers 14‐3‐3 protein binding. Biochem Biophys Res Commun 377: 809–814, 2008.
 171.Raingo J, Khvotchev M, Liu P, Darios F, Li YC, Ramirez DM, Adachi M, Lemieux P, Toth K, Davletov B, Kavalali ET. VAMP4 directs synaptic vesicles to a pool that selectively maintains asynchronous neurotransmission. Nat Neurosci 15: 738–45, 2012.
 172.Ramakrishnan NA, Drescher MJ, Drescher DG. Direct interaction of otoferlin with syntaxin 1A, SNAP‐25, and the L‐type voltage‐gated calcium channel Cav1.3. J Biol Chem 284: 1364–1372, 2009.
 173.Ramirez DM, Khvotchev M, Trauterman B, Kavalali ET. Vti1a identifies a vesicle pool that preferentially recycles at rest and maintains spontaneous neurotransmission. Neuron 73: 121–134, 2012.
 174.Raptis A, Torrejón‐Escribano B, Gómez de Aranda I, Blasi J. Distribution of synaptobrevin/VAMP 1 and 2 in rat brain. J Chem Neuroanat 30: 201–211, 2005.
 175.Reim K, Mansour M, Varoqueaux F, McMahon HT, Südhof TC, Brose N, Rosenmund C. Complexins regulate a late step in Ca2+‐dependent neurotransmitter release. Cell 104: 71–81, 2001.
 176.Reisinger C, Yelamanchili SV, Hinz B, Mitter D, Becher A, Bigalke H, Ahnert‐Hilger G. The synaptophysin/synaptobrevin complex dissociates independently of neuroexocytosis. J Neurochem 90: 1–8, 2004.
 177.Reisinger E, Bresee C, Neef J, Nair R, Reuter K, Bulankina A, Nouvian R, Koch M, Bückers J, Kastrup L, Roux I, Petit C, Hell SW, Brose N, Rhee JS, Kügler S, Brigande JV, Moser T. Probing the functional equivalence of otoferlin and synaptotagmin 1 in exocytosis. J Neurosci 31: 4886–4895, 2011.
 178.Rhee JS, Betz A, Pyott S, Reim K, Varoqueaux F, Augustin I, Hesse D, Südhof TC, Takahashi M, Rosenmund C, Brose N. Beta phobol ester‐ and diacylglycerol‐induced augmentation of transmitter release is mediated by Munc13s and not by PKCs. Cell 108: 121–133, 2002.
 179.Rhee JS, Li LY, Shin OH, Rah JC, Rizo J, Südhof TC, Rosenmund C. Augmenting neurotransmitter release by enhancing the apparent Ca2+ affinity of synaptotagmin 1. Proc Natl Acad Sci U S A 102:18664–18669, 2005.
 180.Rickman C, Archer DA, Meunier FA, Craxton M, Fukuda M, Burgoyne RD, Davletov B. Synaptotagmin interaction with the syntaxin/SNAP‐25 dimer is mediated by an evolutionarily conserved motif and is sensitive to inositol hexakisphosphate. J Biol Chem 279: 12574–12579, 2004.
 181.Rickman C, Davletov B. Arachidonic acid allows SNARE complex formation in the presence of Munc18. Chem Biol 12: 545–553, 2005.
 182.Riedel D, Antonin W, Fernandez‐Chacon R, Alvarez de Toledo G, Jo T, Geppert M, Valentijn K, Jamieson JD, Südhof TC, Jahn R. Rab3D is not required for exocrine exocytosis but for maintenance of normally sized secretory granules. Mol Cell Biol 22: 6487–6497, 2002.
 183.Rituper B, Flašker A, Guček A, Chowdhury HH, Zorec R. Cholesterol and regulated exocytosis: A requirement for unitary exocytotic events. Cell Calcium 52: 250–258, 2012.
 184.Rizo J, Südhof TC. C2‐domains, structure and function of a universal Ca2+‐binding domain. J Biol Chem 273: 15879–15882, 1998.
 185.Rizo J. Synaptotagmin‐SNARE coupling enlightened. Nat Struct Mol Biol 17: 260–262, 2010.
 186.Robinson IM, Ranjan R, Schwarz TL. Synaptotagmins I and IV promote transmitter release independently of Ca2+ binding in the C2A domain. Nature 418: 336–340, 2002.
 187.Rosahl TW, Geppert M, Spillane D, Herz J, Hammer RE, Malenka RC, Südhof TC. Short‐term synaptic plasticity is altered in mice lacking synapsin I. Cell 75: 661–670, 1993.
 188.Rosahl TW, Spillane D, Missler M, Herz J, Selig DK, Wolff JR, Hammer RE, Malenka RC, Südhof TC. Essential functions of synapsin I and II in synaptic vesicle regulation. Nature 375: 488–493, 1995.
 189.Rothman JE. Mechanisms of intracellular protein transport. Nature 372: 55–63, 1994.
 190.Roux I, Safieddine S, Nouvian R, Grati M, Simmler MC, Bahloul A, Perfettini I, Le Gall M, Rostaing P, Hamard G, Triller A, Avan P, Moser T, Petit C. Otoferlin, defective in a human deafness form, is essential for exocytosis at the auditory ribbon synapse. Cell 127: 277–289, 2006.
 191.Rozas JL, Gómez‐Sánchez L, Mircheski J, Linares‐Clemente P, Nieto‐González JL, Vázquez ME, Luján R, Fernández‐Chacón R. Motorneurons require cysteine string protein‐α to maintain the readily releasable vesicular pool and synaptic vesicle recycling. Neuron 74: 151–165, 2012.
 192.Rubenstein JL, Greengard P, Czernik AJ. Calcium‐dependent serine phosphorylation of synaptophysin. Synapse 13: 161–172, 1993.
 193.Rudolf R, Bittins CM, Gerdes HH. The role of myosin V in exocytosis and synaptic plasticity. J Neurochem 116: 177–191, 2011.
 194.Saheki Y, De Camilli P. Synaptic vesicle endocytosis. Cold Spring Harb Perspect Biol 4: a005645, 2012.
 195.Salaün C, James DJ, Chamberlain LH. Lipid rafts and the regulation of exocytosis. Traffic 5: 255–264, 2004.
 196.Schivell AE, Mochida S, Kensel–Hammes P, Custer KL, Bajjalieh SM. SV2A and SV2C contain a unique synaptotagmin‐binding site. Mol Cell Neurosci 29: 56–64, 2005.
 197.Schlüter OM, Schnell E, Verhage M, Tzonopoulos T, Nicoll RA, Jahn R, Malenka RC, Geppert M, Südhof TC. Rabphilin knock‐out mice reveal that rabphilin is not required for rab3 function in regulating neurotransmitter release. J Neurosci 19: 5834–5846, 1999.
 198.Schlüter OM, Schmitz F, Jahn R, Rosenmund C, Südhof TC. A complete genetic analysis of neuronal Rab3 function. J Neurosci 24: 6629–6637, 2004.
 199.Schlüter OM, Basu J, Südhof TC, Rosenmund C. Rab3 superprimes synaptic vesicles for release: Implications for short‐term synaptic plasticity. J Neurosci 26: 1239–1246, 2006.
 200.Schoch S, Deák F, Königstorfer A, Mozhayeva M, Sara Y, Südhof TC, Kavalali ET. SNARE function analyzed in synaptobrevin/VAMP knockout mice. Science 294: 1117–1122, 2001.
 201.Schonn JS, Maximov A, Lao Y, Südhof TC, Sørensen JB. Synaptotagmin‐1 and ‐7 are functionally overlapping Ca2+ sensors for exocytosis in adrenal chromaffin cells. Proc Natl Acad Sci U S A 105: 3998–4003, 2008.
 202.Schonn JS, van Weering JR, Mohrmann R, Schlüter OM, Südhof TC, de Wit H, Verhage M, Sørensen JB. Rab3 proteins involved in vesicle biogenesis and priming in embryonic mouse chromaffin cells. Traffic 11: 1415–1428, 2010.
 203.Schug N, Braig C, Zimmermann U, Engel J, Winter H, Ruth P, Blin N, Pfister M, Kalbacher H, Knipper M. Differential expression of otoferlin in brain, vestibular system, immature and mature cochlea of the rat. Eur J Neurosci 24: 3372–3380, 2006.
 204.Seabra MC, Goldstein JL, Südhof TC, Brown MS. Rab geranylgeranyl transferase. A multisubunit enzyme that prenylates GTP‐binding proteins terminating in Cys‐X‐Cys or Cys‐Cys. J Biol Chem 267: 14497–14503, 1992.
 205.Shao X, Davletov BA, Sutton RB, Südhof TC, Rizo J. Bipartite Ca2+‐binding motif in C2 domains of synaptotagmin and protein kinase C. Science 273: 248–251, 1996.
 206.Sharma G, Grybko M, Vijayaraghavan S. Action potential‐independent and nicotinic receptor‐mediated concerted release of multiple quanta at hippocampal CA3‐mossy fiber synapses. J Neurosci 28: 2563–2575, 2008.
 207.Shih AM, Shin OH. Interactions among the SNARE proteins and complexin analyzed by a yeast four‐hybrid assay. Anal Biochem 416: 107–111, 2011.
 208.Shin OH, Rizo J, Südhof TC. Synaptotagmin function in dense core vesicle exocytosis studied in cracked PC12 cells. Nat Neurosci 5: 649–656, 2002.
 209.Shin OH, Rhee JS, Tang J, Sugita S, Rosenmund C, Südhof TC. Sr2+ binding to the Ca2+ binding site of the synaptotagmin 1 C2B domain triggers fast exocytosis without stimulating SNARE interactions. Neuron 37: 99–108, 2003.
 210.Shin OH, Maximov A, Lim BK, Rizo J, Südhof TC. Unexpected Ca2+‐binding properties of synaptotagmin 9. Proc Natl Acad Sci U S A 101: 2554–2559, 2004.
 211.Shin OH, Han W, Wang Y, Südhof TC. Evolutionarily conserved multiple C2 domain proteins with two transmembrane regions (MCTPs) and unusual Ca2+ binding properties. J Biol Chem 280: 1641–1651, 2005.
 212.Shin OH, Xu J, Rizo J, Südhof TC. Differential but convergent functions of Ca2+ binding to synaptotagmin‐1 C2 domains mediate neurotransmitter release. Proc Natl Acad Sci USA 106: 16469–16474, 2009.
 213.Shin OH, Lu J, Rhee JS, Tomchick DR, Pang ZP, Wojcik SM, Camacho‐Perez M, Brose N, Machius M, Rizo J, Rosenmund C, Südhof TC. Munc13 C2B domain is an activity‐dependent Ca2+ regulator of synaptic exocytosis. Nat Struct Mol Biol 17: 280–288, 2010.
 214.Shirakawa R, Higashi T, Tabuchi A, Yoshioka A, Nishioka H, Fukuda M, Kita T, Horiuchi H. Munc13‐4 is a GTP‐Rab27‐binding protein regulating dense core granule secretion in platelets. J Biol Chem 279: 10730–10737, 2004.
 215.Siegelbaum SA, Kandel ER. Learning‐related synaptic plasticity: LTP and LTD. Curr Opin Neurobiol 1: 113–120, 1991.
 216.Silva AJ, Rosahl TW, Chapman PF, Marowitz Z, Friedman E, Frankland PW, Cestari V, Cioffi D, Südhof TC, Bourtchuladze R. Impaired learning in mice with abnormal short‐lived plasticity. Curr Biol 6: 1509–1518, 1996.
 217.Sommeijer JP, Leyelt CN. Synaptotagmin‐2 is a reliable marker for parvalbumin positive inhibitory boutons in the mouse visual cortex. PLoS One 7: e35323, 2012.
 218.Spillane DM, Rosahl TW, Südhof TC, Malenka RC. Long‐term potentiation in mice lacking synapsins. Neuropharmacology 34: 1573–1579, 1995.
 219.Spiwoks‐Becker I, Vollrath L, Seeliger MW, Jaissle G, Eshkind LG, Leube RE. Synaptic vesicle alterations in rod photoreceptors of synaptophysin‐deficient mice. Neuroscience 107: 127–142, 2011.
 220.Stenius K, Janz R, Südhof TC, Jahn R. Structure of synaptogyrin (p29) defines novel synaptic vesicle protein. J Cell Biol 131: 1801–1809, 1995.
 221.Stevens RJ, Akbergenova Y, Jorquera RA, Littleton JT. Abnormal synaptic vesicle biogenesis in Drosophila synaptogyrin mutants. J Neurosci 32: 18054–18067, 2012.
 222.Südhof TC, Lottspeich F, Greengard P, Mehl E, Jahn R. A synaptic vesicle protein with a novel cytoplasmic domain and four transmembrane regions. Science 238: 1142–1144, 1987.
 223.Südhof TC, Baumert M, Perin MS, Jahn R. A synaptic vesicle membrane protein is conserved from mammals to Drosophila. Neuron 2: 1475–1481, 1989.
 224.Südhof TC, Czernik AJ, Kao HT, Takei K, Johnston PA, Horiuchi A, Kanazir SD, Wagner MA, Perin MS, De Camilli P, Greengard P. Synapsins: mosaics of shared and individual domains in a family of synaptic vesicle phosphoproteins. Science 245: 1474–1480, 1989.
 225.Südhof TC. Synaptotagmins: Why so many? J Biol Chem 277: 7629–7632, 2002.
 226.Südhof TC. The synaptic vesicle cycle. Annu Rev Neurosci 27: 509–547, 2004.
 227.Südhof TC, Rothman JE. Membrane fusion: Grappling with SNARE and SM proteins. Science 323: 474–477, 2009.
 228.Südhof TC. The presynaptic active zone. Neuron 75: 11–25, 2012.
 229.Sugita S, Janz R, Südhof TC. Synaptogyrins regulate Ca2+‐dependent exocytosis in PC12 cells. J Biol Chem 274: 18893–18901, 1999.
 230.Sugita S, Han W, Butz S, Liu X, Fernández‐Chacón R, Lao Y, Südhof TC. Synaptotagmin VII as a plasma membrane Ca2+ sensor in exocytosis. Neuron 30: 459–473, 2001.
 231.Sugita S, Shin OH, Han W, Lao Y, Südhof TC. Synaptotagmins form a hierarchy of exocytotic Ca2+ sensors with distinct Ca2+ affinities. EMBO J 21: 270–280, 2002.
 232.Sun J, Bronk P, Liu X, Han W, Südhof TC. Synapsins regulate use‐dependent synaptic plasticity in the calyx of Held by a Ca2+/calmodulin‐dependent pathway. Proc Natl Acad Sci U S A 103: 2880–2885, 2006.
 233.Sun J, Pang ZP, Qin D, Fahim AT, Adachi R, Südhof TC. A dual Ca2+‐sensor model for neurotransmitter release in a central synapse. Nature 450: 676–682, 2007.
 234.Takai Y, Sasaki T, Shirataki H, Nakanishi H. Rab3A small GTP‐binding protein in Ca2+‐dependent exocytosis. Genes Cells 1: 615–632, 1996.
 235.Takamori S, Holt M, Stenius K, Lemke EA, Grønborg M, Riedel D, Urlaub H, Schenck S, Brügger B, Ringler P, Müller SA, Rammner B, Gräter F, Hub JS, De Groot BL, Mieskes G, Moriyama Y, Klingauf J, Grubmüller H, Heuser J, Wieland F, Jahn R. Molecular anatomy of a trafficking organelle. Cell 127: 831–846, 2006.
 236.Takeshima H, Shimuta M, Komazaki S, Ohmi K, Nishi M, Iino M, Miyata A, Kangawa K. Mitsugumin29, a novel synaptophysin family member from the triad junction in skeletal muscle. Biochem J 331: 317–322, 1998.
 237.Tang J, Maximov A, Shin OH, Dai H, Rizo J, Südhof TC. A complexin/synaptotagmin 1 switch controls fast synaptic vesicle exocytosis. Cell 126:1175–1187, 2006.
 238.Thiele C, Hannah MJ,Fahrenholz F, Huttner WB. Cholesterol binds to synaptophysin and is required for biogenesis of synaptic vesicles. Nat Cell Biol 2: 42–49, 2000.
 239.Tobaben S, Thakur P, Fernández‐Chacón R, Südhof TC, Rettig J, Stahl B. A trimeric protein complex functions as a synaptic chaperone machine. Neuron 31: 987–999, 2001.
 240.Trimble WS, Cowan DM, Scheller RH. VAMP‐1: A synaptic vesicle‐associated integral membrane protein. Proc Natl Acad Sci U S A 85: 4538–4542, 1988.
 241.Tsuboi T, Fukuda M. Synaptotagmin VII modulates the kinetics of dense‐core vesicle exocytosis in PC12 cells. Genes Cells 12: 511–519, 2007.
 242.Valtorta F, Pennuto M, Bonanomi D, Benfenati F. Synaptophysin: Leading actor or walk‐on role in synaptic vesicle exocytosis? Bioessays 26: 445–453, 2004.
 243.van den Bogaart G, Thutupalli S, Risselada JH, Meyenberg K, Holt M, Riedel D, Diederichsen U, Herminghaus S, Grubmüller H, Jahn R. Synaptotagmin‐1 may be a distance regulator acting upstream of SNARE nucleation. Nat Struct Mol Biol 18: 805–812, 2011.
 244.Vasileva M, Horstmann H, Geumann C, Gitler D, Kuner T. Synapsin‐dependent reserve pool of synaptic vesicles supports replenishment of the readily releasable pool under intense synaptic transmission. Eur J Neurosci 36: 3005–3020, 2012.
 245.Venkatesan K, Alix P, Marquet A, Doupagne M, Niespodziany I, Rogister B, Seutin V. Altered balance between excitatory and inhibitory inputs onto CA1 pyramidal neurons from SV2A‐deficient but not SV2B‐deficient mice. J Neurosci Res 90: 2317‐2327, 2012.
 246.Vennekate W, Schröder S, Lin CC, van den Bogaart G, Grunwald M, Jahn R, Walla PJ. Cis‐ and trans‐membrane interactions of synaptotagmin‐1. Proc Natl Acad Sci USA 109: 11037–11042, 2012.
 247.Wang P, Chicka MC, Bhalla A, Richards DA, Chapman ER. Synaptotagmin VII is targeted to secretory organelles in PC12 cells, where it functions as a high‐affinity calcium sensor. Mol Cell Biol 25: 8693–8702, 2005.
 248.Wang Y, Okamoto M, Schmitz F, Hofmann K, Südhof TC. Rim is a putative Rab3 effector in regulating synaptic‐vesicle fusion. Nature 388: 593–598, 1997.
 249.Wang Z, Chapman ER. Rat and Drosophila synaptotagmin 4 have opposite effects during SNARE‐catalyzed membrane fusion. J Biol Chem 285: 30759–30766, 2010.
 250.Wang Z, Liu H, Gu Y, Chapman ER. Reconstituted synaptotagmin I mediates vesicle docking, priming, and fusion. J Cell Biol 195: 1159–1170, 2011.
 251.Wasser CR, Ertunc M, Liu X, Kavalali ET. Cholesterol‐dependent balance between evoked and spontaneous synaptic vesicle recycling. J Physiol 579: 413–429, 2007.
 252.Wen H, Linhoff MW, McGinley MJ, Li GL, Corson GM, Mandel G, Brehm P. Distinct roles for two synaptotagmin isoforms in synchronous and asynchronous transmitter release at zebrafish neuromuscular junction. Proc Natl Acad Sci U S A 107: 13906–13911, 2010.
 253.Weng N, Baumler MD, Thomas DD, Falkowski MA, Swayne LA, Braun JE, Groblewski GE. Functional role of J domain of cysteine string protein in Ca2+‐dependent secretion from acinar cells. Am J Physiol Gastrointest Liver Physiol 296: G1030–G1039, 2009.
 254.Wenk MR, Pellegrini L, Klenchin VA, Di Paolo G, Chang S, Daniell L, Arioka M, Martin TF, De Camilli P. PIP kinase Iγ is the major PI(4,5)P2 synthesizing enzyme at the synapse. Neuron 32: 79–88, 2001.
 255.Westhead EW. Lipid composition and orientation in secretory vesicles. Ann NY Acad Sci 493: 92–99, 1987.
 256.Whittaker VP. The structure and function of cholinergic synaptic vesicles. Biochem Soc Trans 12: 561–576, 1984.
 257.Wiedenmann B, Franke WW. Identification and localization of synaptophysin, an integral membrane glycoprotein of Mr 38,000 characteristic of presynaptic vesicles. Cell 41: 1017–1028, 1985.
 258.Windoffer R, Borchert‐Stuhltrager M, Haass NK, Thomas S, Hergt M, Bulitta CJ, Leube RE. Tissue expression of the vesicle protein pantophysin. Cell Tissue Res 296: 499–510, 1999.
 259.Xu J, Mashimo T, Südhof TC. Synaptotagmin‐1, ‐2, and ‐9: Ca2+ sensors for fast release that specify distinct presynaptic properties in subsets of neurons. Neuron 54: 567–581, 2007.
 260.Xu J, Pang ZP, Shin OH, Südhof TC. Synaptotagmin‐1 functions as a Ca2+ sensor for spontaneous release. Nat Neurosci 12: 759–766, 2009.
 261.Xu T, Bajjalieh SM. SV2 modulates the size of the readily releasable pool of secretory vesicles. Nat Cell Biol 3, 691–698, 2001.
 262.Xue M, Ma C, Craig TK, Rosenmund C, Rizo J. The Janus‐faced nature of the C2B domain is fundamental for synaptotagmin‐1 function. Nat Struct Mol Biol 15: 1160–1168, 2008.
 263.Xue M, Craig TK, Shin OH, Li L, Brautigam CA, Tomchick DR, Südhof TC, Rosenmund C, Rizo J. Structural and mutational analysis of functional differentiation between synaptotagmins‐1 and ‐7. PLoS One 5: e12544, 2010.
 264.Yang SN, Shi Y, Yang G, Li Y, Yu L, Shin OH, Bacaj T, Südhof TC, Yu J, Berggren PO. Inositol hexakisphosphate suppresses excitatory neurotransmission via synaptotagmin‐1 C2B domain in the hippocampal neuron. Proc Natl Acad Sci USA 109: 12183–12188, 2012.
 265.Yao J, Gaffaney JD, Kwon SE, Chapman ER. Doc2 is a Ca2+ sensor required for asynchronous neurotransmitter release. Cell 147: 666–677, 2011.
 266.Yasunaga S, Grati M, Cohen‐Salmon M, El‐Amraoui A, Mustapha M, Salem N, El‐Zir E, Loiselet J, Petit C. A mutation in OTOF, encoding otoferlin, a FER‐1‐like protein, causes DFNB9, a nonsyndromic form of deafness. Nat Genet 21: 363–369, 1999.
 267.Yelamanchili SV, Reisinger C, Becher A, Sikorra S, Bigalke H, Binz T, Ahnert‐Hilger G. The C‐terminal transmembrane region of synaptobrevin binds synaptophysin from adult synaptic vesicles. Eur J Cell Biol 84: 467–475, 2005.
 268.Yoshihara M, Adolfsen B, Galle KT, Littleton JT. Retrograde signaling by Syt 4 induces presynaptic release and synapse‐specific growth. Science 310: 858–863, 2005.
 269.Yu E, Kanno E, Choi S, Sugimori M, Moreira JE, Llinás RR, Fukuda M. Role of Rab27 in synaptic transmission at the squid giant synapse. Proc Natl Acad Sci U S A 105: 16003–16008, 2008.
 270.Zhang X, Rizo J, Südhof TC. Mechanism of phospholipid binding by the C2A‐domain of synaptotagmin I. Biochemistry 37: 12395–12403, 1998.
 271.Zhang YQ, Henderson MX, Colangelo CM, Ginsberg SD, Bruce C, Wu T, Chandra SS. Identification of CSPα clients reveals a role in dynamin 1 regulation. Neuron 74: 136–150, 2012.
 272.Zhang Z, Bhalla A, Dean C, Chapman ER, Jackson MB. Synaptotagmin IV: a multifunctional regulator of peptidergic nerve terminals. Nat Neurosci 12:163–171, 2009.
 273.Zhang Z, Zhang Z, Jackson MB. Synaptotagmin IV modulation of vesicle size and fusion pores in PC12 cells. Biophys J 98: 968–978, 2010.
 274.Zheng Q, Bobich JA, Vidugiriene J, McFadden SC, Thomas F, Roder J, Jeromin A. Neuronal calcium sensor‐1 facilitates neuronal exocytosis through phosphatidylinositol 4‐kinase. J Neurochem 92: 442–451, 2005.
 275.Zucker RS. Short‐term synaptic plasticity. Annu Rev Neurosci 12: 13–31, 1989.
Further Reading
 1.Chapman ER. How does synaptotagmin trigger neurotransmitter release? Annu Rev Biochem 77: 615–641, 2008.
 2.Jahn R, Lang T, Südhof TC. Membrane fusion. Cell 112: 519–533, 2003.
 3.Martin TF. Role of PI(4,5)P2 in vesicle exocytosis and membrane fusion. Subcell Biochem 59: 111–130, 2012.
 4.Südhof TC, Rizo J. Synaptic vesicle exocytosis. Cold Spring Harb Perspect Biol 3: a005637, 2011.

Further Reading

  • Chapman ER. How does synaptotagmin trigger neurotransmitter release? Annu Rev Biochem 77: 615-641, 2008.
  • Jahn R, Lang T, Südhof TC. Membrane fusion. Cell 112: 519-533, 2003.
  • Martin TF. Role of PI(4,5)P2 in vesicle exocytosis and membrane fusion. Subcell Biochem 59: 111-130, 2012.
  • Südhof TC, Rizo J. Synaptic vesicle exocytosis. Cold Spring Harb Perspect Biol 3: a005637, 2011.

 


Related Articles:

Membrane Fusion
Organization and Dynamics of the Lipid Components of Biological Membranes
Cell Biology of Secretion
Calcium Signaling Systems

Contact Editor

Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite

Ok‐Ho Shin. Exocytosis and Synaptic Vesicle Function. Compr Physiol 2014, 4: 149-175. doi: 10.1002/cphy.c130021