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Cell. 1999 Apr 16;97(2):165-74.

SNARE complex formation is triggered by Ca2+ and drives membrane fusion.

Author information

1
Howard Hughes Medical Institute, Department of Molecular and Cellular Physiology, Stanford University School of Medicine, California 94305-5345, USA.

Abstract

Neurotransmitter exocytosis, a process mediated by a core complex of syntaxin, SNAP-25, and VAMP (SNAREs), is inhibited by SNARE-cleaving neurotoxins. Botulinum neurotoxin E inhibition of norepinephrine release in permeabilized PC12 cells can be rescued by adding a 65 aa C-terminal fragment of SNAP-25 (S25-C). Mutations along the hydrophobic face of the S25-C helix result in SNARE complexes with different thermostabilities, and these mutants rescue exocytosis to different extents. Rescue depends on the continued presence of both S25-C and Ca2+ and correlates with complex formation. The data suggest that Ca2+ triggers S25-C binding to a low-affinity site, initiating trans-complex formation. Pairing of SNARE proteins on apposing membranes leads to bilayer fusion and results in a high-affinity cis-SNARE complex.

PMID:
10219238
DOI:
10.1016/s0092-8674(00)80727-8
[Indexed for MEDLINE]
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