title: VPS21 controls entry of endocytosed and biosynthetic proteins into the yeast prevacuolar compartment.
abstract: Mutations in the VPS (vacuolar protein sorting) genes of Saccharomyces cerevisiae have been used to define the trafficking steps that soluble vacuolar hydrolases take en route from the late Golgi to the vacuole. The class D VPS genes include VPS21, PEP12, and VPS45, which appear to encode components of a membrane fusion complex involved in Golgi-to-endosome transport. Vps21p is a member of the Rab family of small Ras-like GTPases and shows strong homology to the mammalian Rab5 protein, which is involved in endocytosis and the homotypic fusion of early endosomes. Although Rab5 and Vps21p appear homologous at the sequence level, it has not been clear if the functions of these two Rabs are similar. We find that Vps21p is an endosomal protein that is involved in the delivery of vacuolar and endocytosed proteins to the vacuole. Vacuolar and endocytosed proteins accumulate in distinct transport intermediates in cells that lack Vps21p function. Therefore, it appears that Vps21p is involved in two trafficking steps into the prevacuolar/late endosomal compartment.
authors.affiliation: Institute of Molecular Biology, Department of Chemistry, University of Oregon, Eugene, Oregon 97403-1229, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Gerrard
authors.forename: N J
authors.initials: NJ
authors.lastname: Bryant
authors.forename: T H
authors.initials: TH
authors.lastname: Stevens
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D019943:Amino Acid Substitution / Q000235:genetics; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000502:physiology; D001692:Biological Transport; D002268:Carboxypeptidases / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D043402:Cathepsin A; D004705:Endocytosis; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000378:metabolism; D004843:Epistasis, Genetic; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal / Q000235:genetics / Q000502:physiology; D007425:Intracellular Membranes / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D051964:Receptors, Mating Factor; D043563:Receptors, Pheromone; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014617:Vacuoles / Q000378:metabolism*; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D005656:Fungal Proteins; C087335:PEP1 protein, S cerevisiae; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D051964:Receptors, Mating Factor; D043563:Receptors, Pheromone; D011993:Recombinant Fusion Proteins; C081863:STE3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C119627:VPS27 protein, S cerevisiae; D033921:Vesicular Transport Proteins; D000469:Alkaline Phosphatase; D002268:Carboxypeptidases; D043402:Cathepsin A; C022325:aspartic proteinase A; D016282:Aspartic Acid Endopeptidases; D020691:rab GTP-Binding Proteins