title: Small GTPase proteins Rin and Rit Bind to PAR6 GTP-dependently and regulate cell transformation.
abstract: The novel small GTPases Rin and Rit are close relatives of Ras, and recent studies show that they play a role in mediating neuronal differentiation. However, the direct effectors of Rin and Rit have yet to be fully characterized. Here we showed that Rin and Rit directly bind to the PDZ domain of PAR6, a cell polarity-regulating protein, in a GTP-dependent manner both in vivo and in vitro. Moreover, Rin and Rit can form a ternary complex consisting of PAR6 and Rac/Cdc42, members of the Rho family of small GTPases modulating cell growth and polarity. This ternary complex synergistically potentiates cell transformation in NIH3T3 cells, and the interaction between Rin/Rit and the PDZ domain of PAR6 is important for this effect. These results suggest that the Rin/Rit-PAR6-Rac/Cdc42 ternary complex may work physiologically in the cells, such as in tumorigenesis.
authors.affiliation: Department of Biochemistry and Cellular Biology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan. hoshinom@ncnp.go.jp
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Hoshino
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Yoshimori
authors.forename: Shun
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002471:Cell Transformation, Neoplastic; D005982:Glutathione Transferase / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D047468:Immunoprecipitation; D051379:Mice; D041681:NIH 3T3 Cells; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry; D014162:Transfection; D020798:Two-Hybrid System Techniques; D001616:beta-Galactosidase / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D011506:Proteins; D011994:Recombinant Proteins; D006160:Guanosine Triphosphate; D005982:Glutathione Transferase; D001616:beta-Galactosidase; C401848:Rin protein (GTPase); C472865:Rit1 protein, mouse; D020764:cdc42 GTP-Binding Protein; D018631:ras Proteins