The docking stage of yeast vacuole fusion requires the transfer of proteins from a cis-SNARE complex to a Rab/Ypt protein.
The homotypic fusion of yeast vacuoles requires Sec18p (NSF)-driven priming to allow vacuole docking, but the mechanism that links priming and docking is unknown. We find that a large multisubunit protein called the Vam2/6p complex is bound to cis-paired SNAP receptors (SNAREs) on isolated vacuoles. This association of the Vam2/6p complex with the cis-SNARE complex is disrupted during priming. The Vam2/6p complex then binds to Ypt7p, a guanosine triphosphate binding protein of the Rab family, to initiate productive contact between vacuoles. Thus, cis-SNARE complexes can contain Rab/Ypt effectors, and these effectors can be mobilized by NSF/Sec18p-driven priming, allowing their direct association with a Rab/Ypt protein to activate docking.
Price
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Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755-3844, USA.
Seals
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Wickner
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Ungermann
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C
D033942:Adaptor Proteins, Vesicular Transport; D000251:Adenosine Triphosphatases; D002352:Carrier Proteins / Q000302:isolation & purification / Q000502:physiology; D005656:Fungal Proteins / Q000502:physiology; D008561:Membrane Fusion / Q000502:physiology*; D008565:Membrane Proteins / Q000302:isolation & purification / Q000502:physiology*; D008954:Models, Biological; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins / Q000302:isolation & purification / Q000502:physiology; D050600:SNARE Proteins; D012441:Saccharomyces cerevisiae / Q000502:physiology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D014617:Vacuoles / Q000502:physiology* / Q000648:ultrastructure; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins / Q000502:physiology*
D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; C077734:NPL3 protein, S cerevisiae; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; C406817:VAM6 protein, S cerevisiae; C083878:VPS41 protein, S cerevisiae; D033921:Vesicular Transport Proteins; D000251:Adenosine Triphosphatases; C064404:SEC18 protein, S cerevisiae; C079005:YPT7 protein, S cerevisiae; D020691:rab GTP-Binding Proteins