title: Tyr-phosphorylation signals translocate RIN3, the small GTPase Rab5-GEF, to early endocytic vesicles.
abstract: The small GTPase Rab5 plays a key role in early endocytic pathway, and its activation requires guanine-nucleotide exchange factors (GEFs). Rab5-GEFs share a conserved VPS9 domain for the GEF action, and RIN3 containing additional domains, such as Src-homology 2, RIN-family homology (RH), and Ras-association (RA), was identified as a new Rab5-GEF. However, precise functions of the additional domains and the activation mechanism of RIN3 remain unknown. Here, we found tyrosine-phosphorylation signals are involved in the Rab5-GEF activation. Treatment of HeLa cells with pervanadate translocates RIN3 from cytoplasm to the Rab5-positive vesicles. This RIN3 translocation was applied to various mutants lacking each domain of RIN3. Our present results suggest that a Ras GTPase(s) activated by tyrosine-phosphorylation signals interacts with the inhibitory RA domain, resulting in an active conformation of RIN3 as a Rab5-GEF and that RIN-unique RH domain constitutes a Rab5-binding region for the progress of GEF action.
authors.affiliation: Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Yoshikawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kajiho
authors.forename: Kyoko
authors.initials: K
authors.lastname: Sakurai
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Minoda
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakagawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Kontani
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Katada
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D010766:Phosphorylation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors; D017384:Sequence Deletion; D022161:Transport Vesicles / Q000378:metabolism*; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*; D014638:Vanadates / Q000494:pharmacology; D020696:rab5 GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D020662:Guanine Nucleotide Exchange Factors; C487967:RIN3 protein, human; C076715:pervanadate; D014638:Vanadates; D014443:Tyrosine; D017027:Protein Tyrosine Phosphatases; D020696:rab5 GTP-Binding Proteins