title: Traffic into the prevacuolar/endosomal compartment of Saccharomyces cerevisiae: a VPS45-dependent intracellular route and a VPS45-independent, endocytic route.
abstract: The vps (vacuolar protein sorting) mutants have been used to dissect and characterize the vacuolar biogenesis pathway in the yeast Saccharomyces cerevisiae. The vps mutants were isolated through their loss of ability to correctly sort the vacuolar hydrolase CPY, which travels from Golgi membranes to the vacuole through a prevacuolar compartment. Over 50 VPS genes have been divided into 6 classes according to vacuolar morphology. Mutations in any one of the class E VPS genes, such as VPS27, lead to an exaggerated form of the prevacuolar compartment. This class E compartment contains endocytosed proteins as well as proteins en route to the vacuole, and is thus taken to represent an intersection point between the endocytic and biosynthetic pathways. Mutations in the class D gene VPS45 can be used to define a second transport intermediate along the vacuolar biogenesis pathway, Golgi-derived transport vesicles carrying vacuolar membrane proteins on their way to the vacuole. Here we demonstrate that the Sec1p-like protein Vps45p is required for the fusion of Golgi-derived vesicles with the prevacuolar compartment indicating that VPS45 functions before VPS27 in the vacuolar biogenesis pathway. In addition, we show that VPS45 function is not required for the delivery of endocytosed proteins to the prevacuolar compartment from the plasma membrane suggesting that the function of Vps45p is restricted to a single vesicular pathway.
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene 97403-1229, USA.
authors.forename: N J
authors.initials: NJ
authors.lastname: Bryant
authors.forename: R C
authors.initials: RC
authors.lastname: Piper
authors.forename: S R
authors.initials: SR
authors.lastname: Gerrard
authors.forename: T H
authors.initials: TH
authors.lastname: Stevens
mesh_terms: D001692:Biological Transport; D002268:Carboxypeptidases / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D043402:Cathepsin A; D002451:Cell Compartmentation; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism*; D004843:Epistasis, Genetic; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D051964:Receptors, Mating Factor; D043563:Receptors, Pheromone; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014617:Vacuoles / Q000378:metabolism*; D033921:Vesicular Transport Proteins
chemical_list: D002352:Carrier Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; C087335:PEP1 protein, S cerevisiae; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D051964:Receptors, Mating Factor; D043563:Receptors, Pheromone; C081863:STE3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C092934:VPS45 protein, S cerevisiae; D033921:Vesicular Transport Proteins; D002268:Carboxypeptidases; D043402:Cathepsin A; D019204:GTP-Binding Proteins; C064553:VPS1 protein, S cerevisiae