title: Identification of a PDZ protein, PIST, as a binding partner for Rho effector Rhotekin: biochemical and cell-biological characterization of Rhotekin-PIST interaction.
abstract: Among various effector proteins for the small GTPase Rho, the function(s) of Rhotekin is (are) almost unknown. We have identified PIST [PDZ (PSD-95, Discs-large and ZO-1) domain protein interacting specifically with TC10 (a Rho-family small GTPase)] as a binding partner for Rhotekin, using yeast two-hybrid screening. Rhotekin was found to associate with PIST in vitro and in both polarized and non-polarized MDCK (Madin-Darby canine kidney) cells. The C-terminal SPV (Ser-Pro-Val) motif of Rhotekin exhibited binding to the PDZ domain of PIST. The binding was markedly inhibited by an activated version of Rho and partially by that of Rac or Cdc42 in COS7 cells. In contrast, TC10 had no effects on the binding. Immunofluorescence analyses revealed the co-localization of PIST and Rhotekin at the Golgi apparatus in non-polarized fibroblast-like MDCK cells and AJs (adherens junctions) in the fully polarized cells. PIST and Rhotekin are recruited from the cytosol to AJs as the cell becomes polarized. Expression of constitutively active Rho or prevention of Rhotekin-PIST interaction induced diffuse cytoplasmic distribution of Rhotekin in polarized MDCK cells. These results suggest that there is (1) Rho-dependent regulation of Rhotekin-PIST interaction, (2) involvement of PIST in the recruitment of Rhotekin to AJs and (3) a possible role(s) for these two proteins in cell-polarity development and/or maintenance.
authors.affiliation: Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, 713-8 Kamiya-Cho, Kasugai, Aichi 480-0392, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Ito
authors.forename: Ikuko
authors.initials: I
authors.lastname: Iwamoto
authors.forename: Rika
authors.initials: R
authors.lastname: Morishita
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nozawa
authors.forename: Tomiko
authors.initials: T
authors.lastname: Asano
authors.forename: Koh-ichi
authors.initials: K
authors.lastname: Nagata
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D016764:Cell Polarity; D002522:Chlorocebus aethiops; D004285:Dogs; D006056:Golgi Apparatus / Q000378:metabolism; D000077614:Golgi Matrix Proteins; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D051379:Mice; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020798:Two-Hybrid System Techniques; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D000077614:Golgi Matrix Proteins; C435484:Gopc protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D020741:rho GTP-Binding Proteins