A family of small coiled-coil-forming proteins functioning at the late endosome in yeast.
The multispanning membrane protein Ste6, a member of the ABC-transporter family, is transported to the yeast vacuole for degradation. To identify functions involved in the intracellular trafficking of polytopic membrane proteins, we looked for functions that block Ste6 transport to the vacuole upon overproduction. In our screen, we identified several known vacuolar protein sorting (VPS) genes (SNF7/VPS32, VPS4, and VPS35) and a previously uncharacterized open reading frame, which we named MOS10 (more of Ste6). Sequence analysis showed that Mos10 is a member of a small family of coiled-coil-forming proteins, which includes Snf7 and Vps20. Deletion mutants of all three genes stabilize Ste6 and show a "class E vps phenotype." Maturation of the vacuolar hydrolase carboxypeptidase Y was affected in the mutants and the endocytic tracer FM4-64 and Ste6 accumulated in a dot or ring-like structure next to the vacuole. Differential centrifugation experiments demonstrated that about half of the hydrophilic proteins Mos10 and Vps20 was membrane associated. The intracellular distribution was further analyzed for Mos10. On sucrose gradients, membrane-associated Mos10 cofractionated with the endosomal t-SNARE Pep12, pointing to an endosomal localization of Mos10. The growth phenotypes of the mutants suggest that the "Snf7-family" members are involved in a cargo-specific event.
Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany.
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D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001693:Biological Transport, Active; D002268:Carboxypeptidases / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D043402:Cathepsin A; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005800:Genes, Fungal; D006023:Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism; D008566:Membranes / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D010641:Phenotype; D050765:Qa-SNARE Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014617:Vacuoles / Q000378:metabolism
D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D005656:Fungal Proteins; D006023:Glycoproteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; C081224:PEP12 protein, S cerevisiae; D050765:Qa-SNARE Proteins; C083890:SNF7 protein, S cerevisiae; C489277:STE6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C430215:VPS60 protein, S cerevisiae; D002268:Carboxypeptidases; D043402:Cathepsin A