The SNARE hypothesis holds that a transport vesicle chooses its target for fusion when a soluble NSF attachment protein (SNAP) receptor on the vesicle (v-SNARE) pairs with its cognate t-SNARE at the target membrane. Three synaptosomal membrane proteins have previously been identified: syntaxin, SNAP-25 (t-SNAREs), and vesicle-associated membrane protein (VAMP) (v-SNARE); all assemble with SNAPs and NSF into 20S fusion particles. We now report that in the absence of SNAP and NSF, these three SNAREs form a stable complex that can also bind synaptotagmin. Synaptotagmin is displaced by α-SNAP, suggesting that these two proteins share binding sites on the SNARE complex and implying that synaptotagmin operates as a "clamp" to prevent fusion from proceeding in the absence of a signal. The α-SNAP-SNARE complex can bind NSF, and NSF-dependent hydrolysis of ATP dissociates the complex, separating syntaxin, SNAP-25, and VAMP. ATP hydrolysis by NSF may provide motion to initiate bilayer fusion.
|Number of pages||10|
|State||Published - Nov 5 1993|
Bibliographical noteFunding Information:
Correspondence should be addressed to J. E. Ft. We thank Masami Nagahama for construction of the His+,-NSF-Myc clone, Willa Bellamy for help with the manuscript, and Wayne Patton for gel scans and analysis. This work was supported by a National Institutes of Health grant to J. E. R., by the Matherscharitable Foundation and a National Institute of Mental Health grant to R. Ii. S., by a fellowship of the Deutsche Forschungsgemeinschaft to T. S., and by a fellowship from the Jane Coffin Childs Memorial Fund for Medical Research to s. w. w.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology (all)