title: Fusion proteins and select lipids cooperate as membrane receptors for the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) Vam7p.
abstract: Vam7p, the vacuolar soluble Qc-SNARE, is essential for yeast vacuole fusion. The large tethering complex, homotypic fusion and vacuole protein sorting complex (HOPS), and phosphoinositides, which interact with the Vam7p PX domain, have each been proposed to serve as its membrane receptors. Studies with the isolated organelle cannot determine whether these receptor elements suffice and whether ligands or mutations act directly or indirectly on Vam7p binding to the membrane. Using pure components that are active in reconstituted vacuolar fusion, we now find that Vam7p binds to membranes through its combined affinities for several vacuolar membrane constituents: HOPS, phosphatidylinositol 3-phosphate, SNAREs, and acidic phospholipids. Acidic lipids allow low concentrations of Vam7p to suffice for fusion; without acidic lipids, the block to fusion is partially bypassed by high concentrations of Vam7p.
authors: From the Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hamshire 03755-3844.
authors: Vidya
authors: V
authors: Karunakaran
authors: William
authors: W
authors: Wickner
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D005454:Fluorescence Polarization; D005978:Glutathione / Q000378:metabolism; D008055:Lipids / Q000737:chemistry*; D008561:Membrane Fusion; D046912:Multiprotein Complexes / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D011485:Protein Binding; D011510:Proteolipids / Q000378:metabolism; D050600:SNARE Proteins / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D050825:Synaptosomal-Associated Protein 25 / Q000378:metabolism*
chemical_list: D008055:Lipids; D046912:Multiprotein Complexes; D010716:Phosphatidylinositols; D011510:Proteolipids; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D050825:Synaptosomal-Associated Protein 25; C494205:VAM7 protein, S cerevisiae; C020485:proteoliposomes; D005978:Glutathione
keywords: Fusion Protein; Lipids; Membrane Fusion; SNARE; Vacuole; Yeast
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