Docking of yeast vacuoles is catalyzed by the Ras-like GTPase Ypt7p after symmetric priming by Sec18p (NSF).
Vacuole inheritance in yeast involves the formation of tubular and vesicular "segregation structures" which migrate into the bud and fuse there to establish the daughter cell vacuole. Vacuole fusion has been reconstituted in vitro and may be used as a model for an NSF-dependent reaction of priming, docking, and fusion. We have developed biochemical and microscopic assays for the docking step of in vitro vacuole fusion and characterized its requirements. The vacuoles must be primed for docking by the action of Sec17p (alpha-SNAP) and Sec18p (NSF). Priming is necessary for both fusion partners. It produces a labile state which requires rapid docking in order to lead productively to fusion. In addition to Sec17p/Sec18p, docking requires the activity of the Ras-like GTPase Ypt7p. Unlike Sec17p/Sec18p, which must act before docking, Ypt7p is directly involved in the docking process itself.
Mayer
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A
Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755-3844, USA.
Wickner
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W
D000251:Adenosine Triphosphatases; D000255:Adenosine Triphosphate / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002458:Cell Fractionation; D003600:Cytosol / Q000378:metabolism; D019281:Dimerization; D005656:Fungal Proteins / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007700:Kinetics; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000378:metabolism; D008853:Microscopy; D009154:Mutation; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D013696:Temperature; D013879:Thioredoxins / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism*; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins
D002352:Carrier Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; C068476:PBI2 protein, S cerevisiae; D012097:Repressor Proteins; C075137:SEC17 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; D033921:Vesicular Transport Proteins; D013879:Thioredoxins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; C064404:SEC18 protein, S cerevisiae; C079005:YPT7 protein, S cerevisiae; D020691:rab GTP-Binding Proteins