Yop1p, the yeast homolog of the polyposis locus protein 1, interacts with Yip1p and negatively regulates cell growth.
Rab proteins are small GTPases that are essential elements of the protein transport machinery of eukaryotic cells. Each round of membrane transport requires a cycle of Rab protein nucleotide binding and hydrolysis. We have recently characterized a protein, Yip1p, which appears to play a role in Rab-mediated membrane transport in Saccharomyces cerevisiae. In this study, we report the identification of a Yip1p-associated protein, Yop1p. Yop1p is a membrane protein with a hydrophilic region at its N terminus through which it interacts specifically with the cytosolic domain of Yip1p. Yop1p could also be coprecipitated with Rab proteins from total cellular lysates. The TB2 gene is the human homolog of Yop1p (Kinzler, K. W., Nilbert, M. C., Su, L.-K., Vogelstein, B., Bryan, T. M., Levey, D. B., Smith, K. J., Preisinger, A. C., Hedge, P., McKechnie, D., Finniear, R., Markham, A., Groffen, J., Boguski, M. S., Altschul, S. F., Horii, A., Ando, H. M., Y., Miki, Y., Nishisho, I., and Nakamura, Y. (1991) Science 253, 661-665). Our data demonstrate that Yop1p negatively regulates cell growth. Disruption of YOP1 has no apparent effect on cell viability, while overexpression results in cell death, accumulation of internal cell membranes, and a block in membrane traffic. These results suggest that Yop1p acts in conjunction with Yip1p to mediate a common step in membrane traffic.
Calero
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Department of Molecular Medicine, and Microbiology and Immunology, Cornell University, Ithaca, New York 14830, USA.
Whittaker
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Collins
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D002455:Cell Division / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D017931:DNA Primers; D005656:Fungal Proteins / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D026901:Membrane Transport Proteins; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D017931:DNA Primers; D005656:Fungal Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C426247:REEP5 protein, human; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; C426246:YOP1 protein, S cerevisiae; C414462:Yip1 protein, S cerevisiae