title: A rab protein is required for the assembly of SNARE complexes in the docking of transport vesicles.
abstract: Rab proteins are generally required for transport vesicle docking. We have exploited yeast secretion mutants to demonstrate that a rab protein is required for v-SNAREs and t-SNAREs to assemble. The absence of the rab protein in the docking complex suggests that, in a broad sense, rab proteins participate in a reaction catalyzing SNARE complex assembly. In so doing, rab proteins could help impart an additional layer of specificity to vesicle docking. This mechanism likely involves the Sec1 homolog Sly1, which we identified in isolated docking complexes. We also report the identification of a novel v-SNARE (Ykt6p) component of the yeast ER-Golgi docking complex that has a CAAX box and is predicted to be lipid anchored. The surprising finding that docking complexes can contain many distinct species of SNAREs (Sed5p, Bos1p, Sec22p, Ykt6p, and likely Bet1p, p28, and p14) suggests that multimeric interactions are features of the fusion machinery, and may also improve the fidelity of vesicle targeting.
authors.affiliation: Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
authors.forename: M
authors.initials: M
authors.lastname: Søgaard
authors.forename: K
authors.initials: K
authors.lastname: Tani
authors.forename: R R
authors.initials: RR
authors.lastname: Ye
authors.forename: S
authors.initials: S
authors.lastname: Geromanos
authors.forename: P
authors.initials: P
authors.lastname: Tempst
authors.forename: T
authors.initials: T
authors.lastname: Kirchhausen
authors.forename: J E
authors.initials: JE
authors.lastname: Rothman
authors.forename: T
authors.initials: T
authors.lastname: Söllner
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001692:Biological Transport / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005204:Farnesol / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism*; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D051938:Munc18 Proteins; D052066:N-Ethylmaleimide-Sensitive Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D017368:Protein Prenylation; D050766:Qb-SNARE Proteins; D050683:R-SNARE Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins
chemical_list: C068037:BOS1 protein, S cerevisiae; D002352:Carrier Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins; D050766:Qb-SNARE Proteins; D050683:R-SNARE Proteins; C072520:SLY1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D005204:Farnesol; D019204:GTP-Binding Proteins; C060755:YPT1 protein, S cerevisiae; D052066:N-Ethylmaleimide-Sensitive Proteins; D020691:rab GTP-Binding Proteins