Gabriely G, et al. (2007) Involvement of Specific COPI Subunits in Protein Sorting from the Late Endosome to the Vacuole in Yeast. Mol Cell Biol 27(2):526-40
Abstract: Although COPI function on the early secretory pathway in eukaryotes is well established, earlier studies also proposed a non-conventional role for this coat complex in endocytosis in mammalian cells. Here we present results that suggest an involvement for specific COPI subunits in the late steps of endosomal protein sorting in Saccharomyces cerevisiae. First, we found that carboxypeptidase Y (CPY) was partially missorted to the cell surface in certain mutants of the COPIB sub-complex (COPIb: Sec27, Sec28, and possibly Sec33), which indicates an impairment in endosomal transport. Second, integral membrane proteins destined for the vacuolar lumen (i.e. carboxypeptidase S (CPS1), Fur4, Ste2, and Ste3) accumulated at an aberrant late endosomal compartment in these mutants. The observed phenotypes for COPIb mutants resemble those of class E vacuolar protein sorting (vps) mutants that are impaired in multivesicular body (MVB) protein sorting and biogenesis. Third, we observed physical interactions and co-localization between COPIb subunits and MVB-associated protein, Vps27. Together, our findings suggest that certain COPI subunits could have a direct role in vacuolar protein sorting to the MVB compartment.
|Status: Published||Type: Journal Article||PubMed ID: 17101773|
Topics addressed in this paper
Number of different genes curated to this paper: 10
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