title: VPS27 controls vacuolar and endocytic traffic through a prevacuolar compartment in Saccharomyces cerevisiae.
abstract: Newly synthesized vacuolar hydrolases such as carboxypeptidase Y (CPY) are sorted from the secretory pathway in the late-Golgi compartment and reach the vacuole after a distinct set of membrane-trafficking steps. Endocytosed proteins are also delivered to the vacuole. It has been proposed that these pathways converge at a "prevacuolar" step before delivery to the vacuole. One group of genes has been described that appears to control both of these pathways. Cells carrying mutations in any one of the class E VPS (vacuolar protein sorting) genes accumulate vacuolar, Golgi, and endocytosed proteins in a novel compartment adjacent to the vacuole termed the "class E" compartment, which may represent an exaggerated version of the physiological prevacuolar compartment. We have characterized one of the class E VPS genes, VPS27, in detail to address this question. Using a temperature-sensitive allele of VPS27, we find that upon rapid inactivation of Vps27p function, the Golgi protein Vps10p (the CPY-sorting receptor) and endocytosed Ste3p rapidly accumulate in a class E compartment. Upon restoration of Vps27p function, the Vps10p that had accumulated in the class E compartment could return to the Golgi apparatus and restore correct sorting of CPY. Likewise, Ste3p that had accumulated in the class E compartment en route to the vacuole could progress to the vacuole upon restoration of Vps27p function indicating that the class E compartment can act as a functional intermediate. Because both recycling Golgi proteins and endocytosed proteins rapidly accumulate in a class E compartment upon inactivation of Vps27p, we propose that Vps27p controls membrane traffic through the prevacuolar/endosomal compartment in wild-type cells.
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene 97403-1229, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Piper
authors.forename: A A
authors.initials: AA
authors.lastname: Cooper
authors.forename: H
authors.initials: H
authors.lastname: Yang
authors.forename: T H
authors.initials: TH
authors.lastname: Stevens
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015415:Biomarkers; D002268:Carboxypeptidases / Q000378:metabolism; D043402:Cathepsin A; D002451:Cell Compartmentation / Q000502:physiology; D003001:Cloning, Molecular; D004705:Endocytosis / Q000502:physiology*; D005656:Fungal Proteins / Q000378:metabolism / Q000502:physiology*; D015870:Gene Expression / Q000502:physiology; D005800:Genes, Fungal / Q000502:physiology; D006056:Golgi Apparatus / Q000502:physiology; D008969:Molecular Sequence Data; D011956:Receptors, Cell Surface / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D051964:Receptors, Mating Factor; D043563:Receptors, Pheromone; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure*; D029701:Saccharomyces cerevisiae Proteins; D014617:Vacuoles / Q000378:metabolism* / Q000648:ultrastructure; D033921:Vesicular Transport Proteins
chemical_list: D015415:Biomarkers; D005656:Fungal 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; D033921:Vesicular Transport Proteins; D002268:Carboxypeptidases; D043402:Cathepsin A