Munc18-bound syntaxin readily forms SNARE complexes with synaptobrevin in native plasma membranes

被引:92
作者
Zilly, Felipe E.
Sorensen, Jakob B.
Jahn, Reinhard
Lang, Thorsten
机构
[1] Max Planck Inst Biophys Chem, Dept Neurobiol, D-37077 Gottingen, Germany
[2] Max Planck Inst Biophys Chem, Dept Membrane Biophys, D-37077 Gottingen, Germany
来源
PLOS BIOLOGY | 2006年 / 4卷 / 10期
关键词
D O I
10.1371/journal.pbio.0040330
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Munc18-1, a protein essential for regulated exocytosis in neurons and neuroendocrine cells, belongs to the family of Sec1/Munc18-like (SM) proteins. In vitro, Munc18-1 forms a tight complex with the SNARE syntaxin 1, in which syntaxin is stabilized in a closed conformation. Since closed syntaxin is unable to interact with its partner SNAREs SNAP-25 and synaptobrevin as required for membrane fusion, it has hitherto not been possible to reconcile binding of Munc18-1 to syntaxin 1 with its biological function. We now show that in intact and exocytosis-competent lawns of plasma membrane, Munc18-1 forms a complex with syntaxin that allows formation of SNARE complexes. Munc18-1 associated with membrane-bound syntaxin 1 can be effectively displaced by adding recombinant synaptobrevin but not syntaxin 1 or SNAP-25. Displacement requires the presence of endogenous SNAP-25 since no displacement is observed when chromaffin cell membranes from SNAP-25-deficient mice are used. We conclude that Munc18-1 allows for the formation of a complex between syntaxin and SNAP-25 that serves as an acceptor for vesicle-bound synaptobrevin and that thus represents an intermediate in the pathway towards exocytosis.
引用
收藏
页码:1789 / 1797
页数:9
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