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Updated: May 5, 2026

Analysis of SNARE-mediated Membrane Fusion Using an Enzymatic Cell Fusion Assay
Published on: October 19, 2012
Selective activation of cognate SNAREpins by Sec1/Munc18 proteins
Jingshi Shen1, David C Tareste, Fabienne Paumet
1Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA.
Abstract:
Sec1/Munc18 (SM) proteins are required for every step of intracellular membrane fusion, but their molecular mechanism of action has been unclear. In this work, we demonstrate a fundamental role of the SM protein: to act as a stimulatory subunit of its cognate SNARE fusion machinery. In a reconstituted system, mammalian SNARE pairs assemble between bilayers to drive a basal fusion reaction. Munc18-1/nSec1, a synaptic SM protein required for neurotransmitter release, strongly accelerates this reaction through direct contact with both t- and v-SNAREs. Munc18-1 accelerates fusion only for the cognate SNAREs for exocytosis, therefore enhancing fusion specificity.
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