title: Molecular characterization of mammalian homologues of class C Vps proteins that interact with syntaxin-7.
abstract: Vesicle-mediated protein sorting plays an important role in segregation of intracellular molecules into distinct organelles. Extensive genetic studies using yeast have identified more than 40 vacuolar protein sorting (VPS) genes involved in vesicle transport to vacuoles. However, their mammalian counterparts are not fully elucidated. In this study, we identified two human homologues of yeast Class C VPS genes, human VPS11 (hVPS11) and human VPS18 (hVPS18). We also characterized the subcellular localization and interactions of the protein products not only from these genes but also from the other mammalian Class C VPS homologue genes, hVPS16 and rVPS33a. The protein products of hVPS11 (hVps11) and hVPS18 (hVps18) were ubiquitously expressed in peripheral tissues, suggesting that they have a fundamental role in cellular function. Indirect immunofluorescence microscopy revealed that the mammalian Class C Vps proteins are predominantly associated with late endosomes/lysosomes. Immunoprecipitation and gel filtration studies showed that the mammalian Class C Vps proteins constitute a large hetero-oligomeric complex that interacts with syntaxin-7. These results indicate that like their yeast counterparts, mammalian Class C Vps proteins mediate vesicle trafficking steps in the endosome/lysosome pathway.
authors.affiliation: Department of Neurochemistry, National Institute of Neuroscience, NCNP, Kodaira, Tokyo 187-8502, Japan.
authors.forename: B Y
authors.initials: BY
authors.lastname: Kim
authors.forename: H
authors.initials: H
authors.lastname: Krämer
authors.forename: A
authors.initials: A
authors.lastname: Yamamoto
authors.forename: E
authors.initials: E
authors.lastname: Kominami
authors.forename: S
authors.initials: S
authors.lastname: Kohsaka
authors.forename: C
authors.initials: C
authors.lastname: Akazawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D002522:Chlorocebus aethiops; D004330:Drosophila / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008322:Mammals; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009928:Organ Specificity; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D050765:Qa-SNARE Proteins; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014162:Transfection; D033921:Vesicular Transport Proteins; D016335:Zinc Fingers
chemical_list: D000906:Antibodies; D002352:Carrier Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D050765:Qa-SNARE Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C424438:VPS11 protein, human; C078863:VPS17 protein, S cerevisiae; D033921:Vesicular Transport Proteins