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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
Sec9 is a SNAP-25-like component of a yeast SNARE complex that may be the effector of Sec4 function in exocytosis
P Brennwald1, B Kearns, K Champion
1Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8002.
Abstract:
To identify potential Sec4 effectors, we isolated high copy suppressors of a Sec4 effector domain mutant. The most potent of these was found to be SEC9, a gene required for post-Golgi transport. The sole essential domain of Sec9 has significant sequence similarity to the neuronal protein SNAP-25, a component of the SNARE complex, that is implicated in vesicle targeting and fusion. Analogous to SNAP-25, Sec9 is bound to the yeast plasma membrane and is absent from post-Golgi vesicles. Furthermore, Sec9 is physically associated with two proteins that are homologous to components of the neuronal SNARE complex. Our results identify Sec9 as the yeast cognate of SNAP-25 and suggest that SNARE complexes acting at specific stages of vesicular transport serve as the ultimate targets of regulation by members of the Sec4/Ypt1/Rab family of GTPases.
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