JBC Connect with Cosmo for Collagen Detection

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Sugita, S.
Right arrow Articles by Südhof, T. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sugita, S.
Right arrow Articles by Südhof, T. C.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

Volume 271, Number 3, Issue of January 19, 1996 pp. 1262-1265
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.
Distinct Ca-dependent Properties of the First and Second C-domains of Synaptotagmin I (*)

(Received for publication, October 16, 1995; and in revised form, November 28, 1995)

Shuzo Sugita (1), (§),  Yutaka Hata (1), (¶),  Thomas C. Südhof (1) (2)(**)

From the  (1)Department of Molecular Genetics and (2)Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75235

ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
FOOTNOTES
ACKNOWLEDGEMENTS
REFERENCES

ABSTRACT

Synaptotagmin I (SytI) is a synaptic vesicle protein that binds Ca and is essential for fast, Ca-dependent neurotransmitter release in the hippocampus, suggesting that it serves as a Ca sensor for exocytosis. Although SytI has two cytoplasmic C(2)-domains, only the first C(2)-domain was shown to exhibit Ca regulation; it binds phospholipids and syntaxin in a Ca-dependent manner. By contrast, the second C(2)-domain is inactive in these assays and only binds putative interacting molecules in a Ca-independent manner. We have now discovered in a yeast two-hybrid screen for SytI-interacting molecules that the C(2)-domains of SytI interact with themselves. Using immobilized recombinant C(2)-domains from SytI and SytII, we found that only the second but not the first C(2)-domains of these synaptotagmins are capable of affinity-purifying native rat brain SytI and that this binding is Ca-dependent, suggesting that only the second C(2)-domain is capable of a Ca-triggered self-association. A relatively high Ca concentration (>100 µM) is required for binding in the presence of Mg; Sr and Ba but not Mg can substitute for Ca. Our data suggest that the second C(2)-domain of SytI is also a Ca-regulated domain similar to the first C(2)-domain but with distinct binding activities.

INTRODUCTION

Synaptotagmin I (SytI) (^1)is a member of a family of neuronal proteins that is characterized by a short N-terminal intravesicular sequence, a single transmembrane region, and a large cytoplasmic sequence containing two C(2)-domains (reviewed in Südhof(1995)). Nine synaptotagmin isoforms have been described in mammals (Perin et al., 1990; Geppert et al., 1991;Wendland et al., 1991; Mizuta et al., 1994; Hilbush and Morgan, 1994; Li et al., 1995a; Craxton and Goedert, 1995; Hudson and Birnbaum, 1995), four of which are also found in non-neural tissues (Li et al., 1995a; Hudson and Birnbaum, 1995). At least three synaptotagmins (SytI, SytII, and SytIII) are synaptic vesicle proteins, of which SytIII is present throughout the brain whereas SytI and SytII show restricted complementary expression patterns with partially overlapping distributions (Ullrich et al., 1994). Mice in which the SytI gene has been mutated exhibit a lethal phenotype in which there is a selective loss of fast Ca-dependent neurotransmitter release in hippocampal synapses (Geppert et al., 1994). Spontaneous neurotransmitter release and neurotransmitter release evoked by Ca-independent mechanisms are normal, suggesting an essential role for SytI only in the Ca-dependent last step of membrane fusion. Together with the Ca binding properties of SytI (Li et al., 1995a, 1995b), these data suggest that SytI may serve as an exocytotic Ca sensor.

Based on the presence of C(2)-domains in SytI and the observation that the C(2)-domain confers Ca regulation onto protein kinase C, it was speculated early on that SytI may be a Ca-binding protein (Perin et al., 1990). Indeed, experiments with purified SytI demonstrated that it binds Ca and phospholipids (Brose et al., 1992) and that it undergoes a conformational change as a function of Ca (Davletov and Südhof, 1994). Studies on recombinant C(2)-domains showed that the first C(2)-domain of SytI and of most but not all other synaptotagmins binds phospholipids as a function of Ca (Davletov and Südhof, 1993; Chapman and Jahn, 1994; Ullrich et al., 1994; Li et al., 1995a). In addition, Ca triggers binding of syntaxin to the first C(2)-domain of synaptotagmins with a Ca dependence that is distinct from that of phospholipid binding, implying the presence of two Ca-binding sites in a single C(2)-domain (Li et al., 1995a, 1995b). Surprisingly, the second C(2)-domain of all synaptotagmins is inactive in these assays despite a high degree of sequence homology. Furthermore, the Ca-dependent binding properties of the native cytoplasmic domain of purified brain SytI containing both C(2)-domains has the same properties as the recombinant single first C(2)-domain (Li et al., 1995a, 1995b). Together these data suggest that the known Ca binding properties of SytI can be entirely accounted for by its first C(2)-domain alone and raised the possibility that the second C(2)-domain may not represent a Ca-binding domain. This possibility was supported by the Ca-independent interactions of the second C(2)-domains of synaptotagmins with clathrin AP2 (Zhang et al., 1994; Li et al., 1995a) and with polyanions such as polyinositol phosphates (Fukuda et al., 1994).

We now report the results of a yeast two-hybrid interaction screen for proteins binding to the C(2)-domains of SytI. Unexpectedly, SytI itself was identified as an interacting partner. In vitro binding assays demonstrated a Ca-dependent self-interaction of SytI that is specific for its second C(2)-domain. These data suggest that in addition to the first C(2)-domain, the second C(2)-domain of SytI is a Ca-regulated domain. However, the two C(2)-domains have distinct Ca-regulated properties, suggesting a functional diversification of C(2)-domains in synaptotagmins.

EXPERIMENTAL PROCEDURES

Yeast Two-hybrid (Y2H) Screens and Interaction Assays

A bait vector (pBTM116p65-8) encoding the cytoplasmic domains of SytI starting with the first C(2)-domain was constructed by cloning the 0.9-kilobase pair SmaI-SalI fragment from pGEX65-8 (Davletov et al., 1993) into the same sites of pBTM116 (Vojtek et al., 1993). This results in a vector expressing a LexA-fusion protein with SytI starting at residue 120. A cDNA library was constructed in the NotI site of Y2H prey vector pVP16 (Vojtek et al., 1993) from poly(A)-enriched rat brain RNA using the Life Technologies, Inc. Choice system. Y2H screens were performed essentially as described (Fields and Song, 1989; Vojtek et al., 1993; Hata and Südhof, 1995) by sequentially transfecting yeast strain L40 with the bait vector and the cDNA library using the lithium acetate method (Schiestl and Gietz, 1989). Transformants were plated on selection plates lacking histidine, uracil, tryptophan, lysine, and leucine but containing 2.5 mM 3-amino triazol. Positive clones were picked after 4-6 days of incubation at 30 °C, and the beta-galactosidase activity of the clones was assayed on a nitrocellulose filter. Extrachromosomal DNA from clones that grew in the absence of histidine and were beta-galactosidase positive was isolated using the glass bead method (Ward, 1990). Prey plasmids were rescued in Escherichia coli HB101 cells by electroporation and selection on M9 plates containing 50 mg/liter proline and 0.1 g/liter ampicillin. 14 million yeast transformants with the cDNA library were screened, and 42 clones positive upon retransformation were isolated and sequenced using the dideoxy chain termination method.

Construction of Expression Vectors

The recombinant GST-synaptotagmin fusion proteins used were synthesized from the following expression plasmids in the vector pGEX-KG (Guan and Dixon, 1991) encoding the following residues of SytI and SytII (Perin et al., 1990; Geppert et al., 1991): pGEX65-4 (GSTSytIC(2)-A), residues 140-267; pGEX65-9 (GSTSytIC(2)-B), residues 266-421; pGEX65-8 (GSTSytIC(2)-A/B), residues 120-421; pGEX1071/1081 (GSTSytIIC(2)-A), residues 141-268; pGEX1153/1159 and pGEX1153/1159 (GSTSytIIC(2)-B wild type and mutant, respectively), residues 266-399; pGEX1071/1152 and pGEX1071/1152 (GSTIISytC(2)-A/B wild type and mutant, respectively), residues 141-422. Recombinant proteins were purified on glutathione-agarose and used immobilized on glutathione-agarose without elution. Amounts of proteins used were standardized based on Coomassie Blue-stained SDS gels.

SytI Binding to Recombinant Proteins

One frozen rat brain (Pelfreeze) was homogenized in 11 ml of 4 mM HEPES-NaOH pH 7.4 containing 0.1 g/liter phenylmethylsulfonyl fluoride. The homogenate was extracted for 4 h at 4 °C after addition of 11 ml of 4 mM HEPES-NaOH pH 7.4, 0.1 g/liter phenylmethylsulfonyl fluoride, 0.2 M NaCl, 2% Nonidet P-40, 2 mM EDTA. Insoluble material was removed from the extract by centrifugation (30 min at 100,000 times g), and MgCl(2) was added to the supernatant to 3.5 mM final concentration. 1-ml aliquots of the supernatant were incubated overnight at 4 °C with glutathione-agarose beads (GSH beads) containing 5-10 µg of immobilized GST-fusion proteins with either 3.5 mM CaCl(2) or 5 mM EGTA. The GSH beads were centrifuged, washed 5 times in the respective incubation buffers, and resuspended in 120 µl of SDS-PAGE sample buffer, and 40 µl were analyzed by SDS-PAGE and immunoblotting using antibodies against synaptotagmin I (Cl604.4; kind gift of Dr. R. Jahn, Yale University), syntaxin I (HPC-1), or AP2 (M11AC1; kind gift of M. Robinson, Cambridge). For the experiments testing the effects of various cations, identical procedures were used except that the extraction was performed in the absence of EDTA, no MgCl(2) was added to the extract, and the incubations with the GSH beads and washing steps were carried out with buffers containing 1 mM EGTA, CaCl(2), MgCl(2), BaCl(2), or SrCl(2). The Ca titration experiments were performed similarly except that the different indicated Ca concentrations were used in the incubation buffers.

Miscellaneous Procedures

SDS-PAGE and immunoblotting were performed using standard procedures and antibodies described previously (Laemmli, 1970; Johnston et al., 1989; Li et al., 1995a). Protein assays were performed with the Bio-Rad kit.

RESULTS

Yeast Two-hybrid Screens for Synaptotagmin I Interacting Proteins

We screened 14 million yeast colonies transformed with a rat brain cDNA library with a bait construct encoding the cytoplasmic C(2)-domains of SytI. 42 clones were isolated that demonstrated beta-galactosidase activation after retransformation of the prey plasmids into yeast. Sequencing revealed that most of these clones encoded either novel proteins or proteins unlikely to interact with SytI physiologically (such as mucin apoprotein; data not shown). One positive clone (pPrey820), however, encoded SytI itself, starting at residue 120 immediately N-terminal to the first C(2)-domain and containing its complete C terminus (data not shown). This clone resulted in high beta-galactosidase levels upon co-transformation with the SytI bait construct, confirming an interaction in the Y2H assay.

Ca-dependent Binding of the Second C(2)-domain of SytI to Endogenous Brain SytI

The Y2H result suggested that the C(2)-domains of SytI can interact with themselves. To obtain independent evidence for such an interaction and to localize the interacting sequences, we purified GST-fusion proteins encoding either the first or the second or both C(2)-domains of SytI and SytII. Recombinant proteins were immobilized on glutathione-agarose beads, and binding of endogenous brain SytI to the immobilized fusion proteins was measured as a function of Ca. Fusion proteins containing both C(2)-domains or containing only the second C(2)-domain of either SytI or SytII efficiently affinity-purified SytI from total brain (Fig. 1). Strong binding was observed only in the presence of Ca, whereas in the absence of Ca weak binding was present. By contrast, the first C(2)-domains of SytI and of SytII were unable to bind. A point mutation in the second C(2)-domain of SytII that corresponds to a mutation in Drosophila synaptotagmin, which impairs synaptotagmin function (DiAntonio and Schwarz, 1994), had no effect on Ca-dependent binding. Together these results suggest that the C(2)-domains of synaptotagmins self-associate as a function of Ca via their second but not their first C(2)-domains. Since the low binding observed in the absence of Ca appears to be sufficient for an interaction observed in the Y2H assay, it is possible to identify Ca-dependent binding proteins for SytI using the Ca-independent Y2H screen.

Figure 1: Ca-dependent binding of synaptotagmin I (SytI) from rat brain to recombinant C(2)-domains from SytI and SytII. GST-fusion proteins containing the first C(2)-domain (C(2)-A), the second C(2)-domain (C(2)-B), or both C(2)-domains (C(2)-A/B) of SytI or SytII were immobilized on glutathione beads. Immobilized recombinant proteins were incubated with solubilized rat brain homogenate containing 3.5 mM Mg in the presence or absence of Ca. Beads were washed 5 times, and bound proteins were analyzed by SDS-PAGE and immunoblotting with a monoclonal antibody to the N terminus of SytI that does not recognize the recombinant GST-fusion proteins. Note specific binding only to constructs containing the second C(2)-domain of SytI or SytII. For SytII, a mutant second C(2)-domain corresponding to a mutation observed in Drosophila (DiAntonio and Schwarz, 1994) was also analyzed (indicated by asterisks in protein names). In this mutant tyrosine 312 was changed to asparagine. Numbers on the left indicate positions of molecular weight markers; arrow points to SytI.


Divalent Cation Specificity of Synaptotagmin Self-interaction

Previous studies on the first C(2)-domains of synaptotagmins demonstrated that Sr and Ba but not Mg can substitute for Ca in activating phospholipid binding, although with a much lower affinity (Davletov and Südhof, 1993; Li et al., 1995b). We therefore tested the effects of different divalent cations on the binding of SytI to the second C(2)-domain of SytI (Fig. 2). Mg was unable to trigger binding and in fact inhibited binding compared with that observed in the absence of divalent cations (Fig. 2). By contrast, both Sr and Ba were capable of activating binding, with Ba having the lowest effect. Parallel incubations with GST alone demonstrated that the binding observed was dependent on the SytI-fusion protein and not due to divalent cation-dependent aggregation of SytI in the homogenate (lower panel in Fig. 2).

Figure 2: Cation specificity of the binding of SytI to the recombinant second C(2)-domain of SytI. A recombinant GST-fusion protein with the second C(2)-domain of SytI (top panel labeled GSTSytIC(2)-B) or recombinant GST alone (bottom panel labeled GST) was immobilized on glutathione beads and incubated with solubilized brain homogenates containing either 1 mM EGTA, no additions, or 1 mM of the indicated divalent cations. Beads were washed in the incubation buffers, and bound proteins were analyzed by SDS-PAGE and immunoblotting. The asterisk identifies the position of full-length SytI; the 40-kDa band observed in lanes 3 and 6 containing high levels of bound SytI represents the major proteolytic product of SytI (Perin et al., 1991). Note that addition of Mg slightly suppresses binding. Numbers on the left indicate positions of molecular weight markers.


Ca Dependence of Second C(2)-domain Binding

To test the Ca concentration dependence of the binding of brain SytI to the second C(2)-domains of SytI or SytII, we incubated brain homogenates with immobilized GST-C(2)-domain fusion proteins at different Ca concentrations and analyzed binding of SytI, syntaxin I, and clathrin AP2 to the immobilized proteins as a function of Ca (Fig. 3). As shown earlier (Zhang et al., 1994; Li et al., 1995a), binding of AP2 and syntaxin I to the second C(2)-domain was Ca-independent. By contrast, SytI binding was enhanced by Ca with an identical concentration dependence for the two C(2)-domains tested, with half-maximal binding at approximately 250 µM free Ca. This Ca concentration dependence resembles that of syntaxin I binding to the first C(2)-domain of SytI and SytII (Li et al., 1995a). Note that these experiments were carried out in the presence of 3.5 mM Mg and the apparent Ca affinity may be higher in the absence of Mg.

Figure 3: Ca dependence of SytI binding to the second C(2)-domains of SytI and SytII. Recombinant GST-fusion proteins of the second C(2)-domains of SytI and SytII (GSTSytIC(2)-B and GSTSytIIC(2)-B, respectively) were immobilized and incubated with brain homogenates in Mg-containing buffers with the Ca concentrations indicated on top of the panels (E = EGTA). Beads were washed extensively in the incubation buffers. Bound proteins were analyzed by immunoblotting for the clathrin assembly protein AP2, SytI, and syntaxin I. Numbers on the left indicate positions of molecular weight markers.


DISCUSSION

SytI is a Ca-binding protein of synaptic vesicles that is essential for fast Ca-dependent neurotransmitter release from hippocampal neurons (Brose et al., 1992; Geppert et al., 1994), suggesting that it serves as the exocytotic Ca sensor. Previous studies demonstrated that the first C(2)-domain of SytI serves as a Ca-dependent phospholipid- and syntaxin-binding domain (Davletov and Südhof, 1993, 1994; Li et al., 1995a, 1995b). The second C(2)-domain is inactive in these assays but binds AP2 and polyanions in a Ca-independent manner (Zhang et al., 1994; Fukuda et al., 1994). The phospholipid and syntaxin binding properties of a cytoplasmic fragment from SytI containing both C(2)-domains are identical to that of the single recombinant first C(2)-domain (Li et al., 1995a, 1995b). Together these results suggested that SytI may perform its Ca sensor function primarily via its first C(2)-domain whereas the second C(2)-domain may have a distinct function. We now demonstrate that the second C(2)-domain also has a Ca-dependent activity suggestive of a Ca-binding domain. It mediates the Ca-dependent aggregation of SytI and SytII with a Ca concentration dependence that mirrors the Ca dependence of neurotransmitter release if the experiments are performed in the presence of physiological concentrations of Mg. These data suggest a model of SytI whereby both C(2)-domains of SytI can serve as Ca binding modules with distinct functions (Fig. 4).

Figure 4: Domain model of SytI and its binding activities. SytI binds phospholipids and syntaxin in a Ca-dependent manner via its first C(2)-domain and self-associates in a Ca-dependent manner via its second C(2)-domain. In addition, the N-terminal domains of synaptotagmin I self-associate in a Ca-independent manner via an undetermined sequence, and the C-terminal domains also bind AP2, polyanions such as polyinositol phosphates (IP), and neurexins in a Ca-independent manner (see text for references).


Even in the absence of Ca, SytI is not a monomer but a multimer (Perin et al., 1991). The basic unit of this multimer is an SDS-resistant dimer that can be detected by SDS-PAGE, and this multimerization is mediated by sequences N-terminal to the two C(2)-domains (Brose et al., 1992) (Fig. 4). Our current demonstration of a Ca-dependent binding of SytI to itself via its second C(2)-domain raises the possibility that during nerve terminal depolarization and Ca influx, SytI multimers may be cross-linked by Ca into large superstructures. The function of such a superstructure in fusion is unknown, but it is conceivable that it would aid in forming a pore that must occur during membrane fusion and probably involves assembly of a proteinaceous ring.

A considerable number of interactions has been described for synaptotagmins, not all of which may be physiologically important. Considering the point of action of SytI, it seems likely that Ca-regulated activities are more relevant than constitutive binding activities. Another criterion that supports the potential physiological relevance of an interaction is the colocalization of the binding partners. Based on these two criteria, the interactions of SytI with phospholipids, syntaxin, and itself appear to be the most likely to be relevant. The recombinant second C(2)-domain of SytI also binds syntaxin (see Fig. 3) and phospholipids (Damer and Creutz, 1994) in a Ca-independent manner. However, when the complete double C(2)-domain fragment from native SytI prepared by partial proteolytic cleavage is analyzed, phospholipid binding and syntaxin binding are completely dependent on Ca, and little Ca-independent binding is observed (Li et al., 1995a, 1995b). Two other binding activities were demonstrated for synaptotagmin I that are Ca-independent and conceptually intriguing: binding of neurexins and AP2. Although no in vivo data exist to support the physiological significance of neurexin binding, AP2 binding may be physiologically significant since AP2 transiently associates with synaptic vesicles (Pfeffer and Kelly, 1985; Maycox et al., 1992) and synaptic vesicle recycling is severely impaired in synaptotagmin mutants in Caenorhabditis elegans (Jorgensen et al., 1995).

FOOTNOTES

*
This study was partially supported by a grant from the Perot Family Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked ``advertisement'' in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

§
Supported by a postdoctoral fellowship from the Muscular Dystrophy Association.

Supported by a fellowship from the Human Frontier Science Program. Present address: Takai Biotimer Project, ERATO, 2-2-10 Murotani, Kobe 651-22, Japan.

**
To whom correspondence should be addressed.

(^1)
The abbreviations used are: SytI and SytII, synaptotagmins I and II; Y2H, yeast two-hybrid; GST, glutathione S-transferase; PAGE, polyacrylamide gel electrophoresis.

ACKNOWLEDGEMENTS

We thank A. Roth, E. Borowicz, S. Afendis, and I. Leznicki for excellent technical assistance, Drs. M. S. Brown, Y. Takai, and J. L. Goldstein for advice, and Dr. R. Jahn for discussions. We are grateful to Drs. S. Hollenberg, H. Schulman, M. Robinson, and R. Jahn for supplying us with very helpful reagents.

REFERENCES

  1. Brose, N., Petrenko, A. G., Südhof, T. C., and Jahn, R. (1992) Science 256, 1021-1025 [Abstract/Free Full Text]
  2. Chapman, E. R., and Jahn, R. (1994) J. Biol. Chem. 269, 5735-5741 [Abstract/Free Full Text]
  3. Craxton, M., and Goedert, M. (1995) FEBS Lett. 361, 196-200 [CrossRef][Medline] [Order article via Infotrieve]
  4. Damer, C. K., and Creutz, C. E. (1994) J. Biol. Chem. 269, 31115-31123 [Abstract/Free Full Text]
  5. Davletov, B. A., and Südhof, T. C. (1993) J. Biol. Chem. 268, 26386-26390 [Abstract/Free Full Text]
  6. Davletov, B. A., and Südhof, T. C. (1994) J. Biol. Chem. 269, 28547-28550 [Abstract/Free Full Text]
  7. Davletov, B., Sontag, J. M., Hata, Y., Petrenko, A. G., Fykse, E. M., Jahn, R., and Südhof, T. C. (1993) J. Biol. Chem. 268, 6816-6822 [Abstract/Free Full Text]
  8. DiAntonio, A., and Schwarz, T. L. (1994) Neuron 12, 909-920 [CrossRef][Medline] [Order article via Infotrieve]
  9. Fields, S., and Song, O. (1989) Nature 340, 245-246 [CrossRef][Medline] [Order article via Infotrieve]
  10. Fukuda, M., Aruga, J., Niinobe, M., Aimoto, S., and Mikoshiba, K. (1994) J. Biol. Chem. 269, 29206-29211 [Abstract/Free Full Text]
  11. Geppert, M., Archer, B. T., III, and Südhof, T. C. (1991) J. Biol. Chem. 266, 13548-13552 [Abstract/Free Full Text]
  12. Geppert, M., Goda, Y., Hammer, R. E., Li, C., Rosahl, T. W., Stevens, C. F., and Südhof, T. C. (1994) Cell 79, 717-727 [CrossRef][Medline] [Order article via Infotrieve]
  13. Guan, K. L., and Dixon, J. E. (1991) Anal. Biochem. 192, 262-267 [CrossRef][Medline] [Order article via Infotrieve]
  14. Hata, Y., and Südhof, T. C. (1995) J. Biol. Chem. 270, 13022-13028 [Abstract/Free Full Text]
  15. Hilbush, B. S., and Morgan, J. I. (1994) Proc. Natl. Acad. Sci. U. S. A. 91, 8195-8199 [Abstract/Free Full Text]
  16. Hudson, A. W., and Birnbaum, M. J. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 5895-5899 [Abstract/Free Full Text]
  17. Johnston, P. A., Jahn, R., and Südhof, T. C. (1989) J. Biol. Chem. 264, 1268-1273 [Abstract/Free Full Text]
  18. Jorgensen, E. M., Hartwieg, E., Schuske, K., Nonet, M. L., Jin, Y., and Horvitz, H. R. (1995) Nature 378, 196-199 [CrossRef][Medline] [Order article via Infotrieve]
  19. Laemmli, U. K. (1970) Nature 227, 680-685 [CrossRef][Medline] [Order article via Infotrieve]
  20. Li, C., Ullrich, B., Zhang, J. Z., Anderson, R. G. W., Brose, N., and Südhof, T. C. (1995a) Nature 375, 594-599 [CrossRef][Medline] [Order article via Infotrieve]
  21. Li, C., Davletov, B. A., and Südhof, T. C. (1995b) J. Biol. Chem. 270, 24898-24902 [Abstract/Free Full Text]
  22. Maycox, P. P. R., Link, E., Reetz, A., Morris, S. A., and Jahn, R. (1992) J. Cell Biol. 118, 1379-1388 [Abstract/Free Full Text]
  23. Mizuta, M., Inagake, N., Nemoto, Y., Matsukura, S., Takahashi, M., and Seino, S. (1994) J. Biol. Chem. 269, 11675-11678 [Abstract/Free Full Text]
  24. Perin, M. S., Fried, V., Mignery, G. A., Jahn, R., and Südhof, T. C. (1990) Nature 345, 260-263 [CrossRef][Medline] [Order article via Infotrieve]
  25. Perin, M. S., Brose, N., Jahn, R., and Südhof, T. C. (1991) J. Biol. Chem. 266, 623-629 [Abstract/Free Full Text]
  26. Pfeffer, S. R., and Kelly, R. B. (1985) Cell 40, 949-957 [CrossRef][Medline] [Order article via Infotrieve]
  27. Schiestl, R. H., and Gietz, R. D. (1989) Curr. Genet. 16, 339-346 [CrossRef][Medline] [Order article via Infotrieve]
  28. Südhof, T. C. (1995) Nature 375, 645-653 [CrossRef][Medline] [Order article via Infotrieve]
  29. Ullrich, B., Li, C., Zhang, J. Z., McMahon, H., Anderson, R. G. W., Geppert, M., and Südhof, T. C. (1994) Neuron 13, 1281-1291 [CrossRef][Medline] [Order article via Infotrieve]
  30. Vojtek, A. B., Hollenberg, S. M., and Cooper, J. A. (1993) Cell 74, 205-214 [CrossRef][Medline] [Order article via Infotrieve]
  31. Ward, A. C. (1990) Nucleic Acids Res. 18, 5319 [Free Full Text]
  32. Wendland, B., Miller, K. G., Schilling, J., and Scheller, R. H. (1991) Neuron 6, 993-1007 [CrossRef][Medline] [Order article via Infotrieve]
  33. Zhang, J. Z., Davletov, B. A., Südhof, T. C., and Anderson, R. G. W. (1994) Cell 78, 751-760 [CrossRef][Medline] [Order article via Infotrieve]
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.

Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?


This article has been cited by other articles:


Home page
 Proc. Natl. Acad. Sci. USAHome page
J.-S. Rhee, L. Y. Li, O.-H. Shin, J.-C. Rah, J. Rizo, T. C. Sudhof, and C. Rosenmund
Augmenting neurotransmitter release by enhancing the apparent Ca2+ affinity of synaptotagmin 1
PNAS, December 20, 2005; 102(51): 18664 - 18669.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
W. Han, J.-S. Rhee, A. Maximov, W. Lin, R. E. Hammer, C. Rosenmund, and T. C. Sudhof
C-terminal ECFP Fusion Impairs Synaptotagmin 1 Function: CROWDING OUT SYNAPTOTAGMIN 1
J. Biol. Chem., February 11, 2005; 280(6): 5089 - 5100.
[Abstract] [Full Text] [PDF]

Home page
 NeuroscientistHome page
M. Yoshihara and E. S. Montana
The Synaptotagmins: Calcium Sensors for Vesicular Trafficking
Neuroscientist, December 1, 2004; 10(6): 566 - 574.
[Abstract] [PDF]

Home page
 J. Neurosci.Home page
T.-i. Nishiki and G. J. Augustine
Dual Roles of the C2B Domain of Synaptotagmin I in Synchronizing Ca2+-Dependent Neurotransmitter Release
J. Neurosci., September 29, 2004; 24(39): 8542 - 8550.
[Abstract] [Full Text] [PDF]

Home page
 Biophys. JHome page
R. A. Garcia and H. A. Godwin
High Metal Concentrations Are Required for Self-Association of Synaptotagmin II
Biophys. J., April 1, 2004; 86(4): 2455 - 2466.
[Abstract] [Full Text] [PDF]

Home page
 J. Gen. Physiol.Home page
J. B. Sorensen, R. Fernandez-Chacon, T. C. Sudhof, and E. Neher
Examining Synaptotagmin 1 Function in Dense Core Vesicle Exocytosis under Direct Control of Ca2+
J. Gen. Physiol., August 25, 2003; 122(3): 265 - 276.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
Y. Wu, Y. He, J. Bai, S.-R. Ji, W. C. Tucker, E. R. Chapman, and S.-F. Sui
Visualization of synaptotagmin I oligomers assembled onto lipid monolayers
PNAS, February 18, 2003; 100(4): 2082 - 2087.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
M. Fukuda
Vesicle-associated Membrane Protein-2/Synaptobrevin Binding to Synaptotagmin I Promotes O-Glycosylation of Synaptotagmin I
J. Biol. Chem., August 9, 2002; 277(33): 30351 - 30358.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
M. Fukuda, E. Katayama, and K. Mikoshiba
The Calcium-binding Loops of the Tandem C2 Domains of Synaptotagmin VII Cooperatively Mediate Calcium-dependent Oligomerization
J. Biol. Chem., August 2, 2002; 277(32): 29315 - 29320.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
A. Honda, M. Yamada, H. Saisu, H. Takahashi, K. J. Mori, and T. Abe
Direct, Ca2+-dependent Interaction between Tubulin and Synaptotagmin I. A POSSIBLE MECHANISM FOR ATTACHING SYNAPTIC VESICLES TO MICROTUBULES
J. Biol. Chem., May 31, 2002; 277(23): 20234 - 20242.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
T. C. Sudhof
Synaptotagmins: Why So Many?
J. Biol. Chem., March 1, 2002; 277(10): 7629 - 7632.
[Full Text] [PDF]

Home page
 DiabetesHome page
S. H. Gerber, J. Rizo, and T. C. Sudhof
Role of Electrostatic and Hydrophobic Interactions in Ca2+-Dependent Phospholipid Binding by the C2A-Domain From Synaptotagmin I
Diabetes, February 1, 2002; 51(90001): S12 - 18.
[Abstract] [Full Text] [PDF]

Home page
 Biol. Reprod.Home page
D. M. Hutt, R. A. Cardullo, J. M. Baltz, and J. K. Ngsee
Synaptotagmin VIII Is Localized to the Mouse Sperm Head and May Function in Acrosomal Exocytosis
Biol Reprod, January 1, 2002; 66(1): 50 - 56.
[Abstract] [Full Text]

Home page
 J. Biol. Chem.Home page
M. Fukuda, E. Kanno, Y. Ogata, and K. Mikoshiba
Mechanism of the SDS-resistant Synaptotagmin Clustering Mediated by the Cysteine Cluster at the Interface between the Transmembrane and Spacer Domains
J. Biol. Chem., October 19, 2001; 276(43): 40319 - 40325.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
J. T. Littleton, J. Bai, B. Vyas, R. Desai, A. E. Baltus, M. B. Garment, S. D. Carlson, B. Ganetzky, and E. R. Chapman
synaptotagmin Mutants Reveal Essential Functions for the C2B Domain in Ca2+-Triggered Fusion and Recycling of Synaptic Vesicles In Vivo
J. Neurosci., March 1, 2001; 21(5): 1421 - 1433.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
A. M. Phillips, M. Smith, M. Ramaswami, and L. E. Kelly
The Products of the Drosophila stoned Locus Interact with Synaptic Vesicles via Synaptotagmin
J. Neurosci., November 15, 2000; 20(22): 8254 - 8261.
[Abstract] [Full Text] [PDF]

Home page
 J. Cell Biol.Home page
R. C. Desai, B. Vyas, C. A. Earles, J. T. Littleton, J. A. Kowalchyck, T. F.J. Martin, and E.R. Chapman
The C2B Domain of Synaptotagmin Is a Ca2+-sensing Module Essential for Exocytosis
J. Cell Biol., September 5, 2000; 150(5): 1125 - 1136.
[Abstract] [Full Text] [PDF]

Home page
 J. Cell Biol.Home page
P. J. Plant, F. Lafont, S. Lecat, P. Verkade, K. Simons, and D. Rotin
Apical Membrane Targeting of Nedd4 Is Mediated by an Association of Its C2 Domain with Annexin XIIIb
J. Cell Biol., June 26, 2000; 149(7): 1473 - 1484.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
B. Sampo, N. Tricaud, C. Leveque, M. Seagar, F. Couraud, and B. Dargent
Direct interaction between synaptotagmin and the intracellular loop I-II of neuronal voltage-sensitive sodium channels
PNAS, March 28, 2000; 97(7): 3666 - 3671.
[Abstract] [Full Text] [PDF]

Home page
 Hum Mol GenetHome page
D. B. Davis, A. J. Delmonte, C. T. Ly, and E. M. McNally
Myoferlin, a candidate gene and potential modifier of muscular dystrophy
Hum. Mol. Genet., January 22, 2000; 9(2): 217 - 226.
[Abstract] [Full Text] [PDF]

Home page
 Mol. Biol. CellHome page
A. D. Blagoveshchenskaya, E. W. Hewitt, and D. F. Cutler
Di-Leucine Signals Mediate Targeting of Tyrosinase and Synaptotagmin to Synaptic-like Microvesicles within PC12 Cells
Mol. Biol. Cell, November 1, 1999; 10(11): 3979 - 3990.
[Abstract] [Full Text]

Home page
 J. Biol. Chem.Home page
M. Fukuda, E. Kanno, and K. Mikoshiba
Conserved N-terminal Cysteine Motif Is Essential for Homo- and Heterodimer Formation of Synaptotagmins III, V, VI, and X
J. Biol. Chem., October 29, 1999; 274(44): 31421 - 31427.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
M. Fukuda and K. Mikoshiba
A Novel Alternatively Spliced Variant of Synaptotagmin VI Lacking a Transmembrane Domain. IMPLICATIONS FOR DISTINCT FUNCTIONS OF THE TWO ISOFORMS
J. Biol. Chem., October 29, 1999; 274(44): 31428 - 31434.
[Abstract] [Full Text] [PDF]

Home page
 Physiol. Rev.Home page
A. Meir, S. Ginsburg, A. Butkevich, S. G. Kachalsky, I. Kaiserman, R. Ahdut, S. Demirgoren, and R. Rahamimoff
Ion Channels in Presynaptic Nerve Terminals and Control of Transmitter Release
Physiol Rev, July 1, 1999; 79(3): 1019 - 1088.
[Abstract] [Full Text] [PDF]