title: Rab15 mediates an early endocytic event in Chinese hamster ovary cells.
abstract: Rab GTPases comprise a large family of monomeric proteins that regulate a diverse number of membrane trafficking events, including endocytosis. In this paper, we examine the subcellular distribution and function of the GTPase Rab15. Our biochemical and confocal immunofluorescence studies demonstrate that Rab15 associates with the transferrin receptor, a marker for the early endocytic pathway, but not with Rab7 or the cation-independent mannose 6-phosphate receptor, markers for late endosomal membranes. Furthermore, Rab15 colocalizes with Rab4 and -5 on early/sorting endosomes, as well as Rab11 on pericentriolar recycling endosomes. Consistent with its localization to early endosomal membranes, overexpression of the constitutively active mutant HArab15Q67L reduces receptor-mediated and fluid phase endocytosis. Therefore, our functional studies suggest that Rab15 may function as an inhibitory GTPase in early endocytic trafficking.
authors.affiliation: Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Zuk
authors.forename: L A
authors.initials: LA
authors.lastname: Elferink
mesh_terms: D000818:Animals; D015415:Biomarkers; D016466:CHO Cells / Q000502:physiology*; D002451:Cell Compartmentation; D002458:Cell Fractionation; D002502:Centrioles / Q000502:physiology; D006224:Cricetinae; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000502:physiology*; D019084:Fluorescent Antibody Technique, Indirect; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000302:isolation & purification*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000302:isolation & purification*; D009154:Mutation; D011990:Receptors, Transferrin / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000302:isolation & purification; D020691:rab GTP-Binding Proteins; D020695:rab4 GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins
chemical_list: D015415:Biomarkers; D011990:Receptors, Transferrin; D011994:Recombinant Proteins; C120765:rab15 protein, hamster; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020691:rab GTP-Binding Proteins; D020695:rab4 GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins