SNARE-zippering

Breton, M., Anne, C., Darchen, F. 2008. A fast mode of membrane fusion dependent on tight SNARE zippering. J. Neurosci. 28 8470-8476. 

SNARE proteins assemble into a heterotrimeric SNARE complex (or core complex). The crystal structure of the core complex revealed a bundle of four a-helices, one each contributed by synaptobrevin and syntaxin and two contributed by SNAP-25 (28). The process of SNARE complex assembly proceeds from N-terminal to C-terminal direction in what is commonly referred to as a zippering action, which brings the C-terminal membrane anchors of the transSNAREs together (29). This action is proposed to force the closely apposed membranes together to initiate fusion. 

It is now well established that in vivo efficient membrane fusion requires the interaction of small cytoplasmically exposed membrane proteins called soluble N-ethylmaleimide sensitive factor (NSF) attachment receptors (SNAREs) (Sollner et al., 1993). For synaptic vesicle exocytosis, the relevant SNAREs are synaptobrevin/ vesicle-associated membrane protein (VAMP) 1 and 2, syntaxin 1, and synaptosome-associ-ated protein of 25,000 daltons (SNAP-25). Synaptobrevins/ VAMPs are localized primarily on synaptic vesicles, while syntaxin and SNAP-25 are localized primarily on the plasma membrane. Fusion is driven by the progressive zippering of vesicle and plasma membrane SNAREs forming a four-helix bundle (Sutton et al., 1998). Although many other proteins appear to play critical roles in synaptic vesicle exocytosis, it seems likely that SNAREs are the minimal machinery required for fusion (Weber et al., 1998). Once assembled, SNARE complexes are disassembled by NSF, which functions in conjunction with SNAP proteins. 

Study of Exocytosis with an Artificial Cell Model Using a DNA Zipper as a SNARE-Protein Mimic... 

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