title: Type 5 G protein beta subunit (Gbeta5) controls the interaction of regulator of G protein signaling 9 (RGS9) with membrane anchors.
abstract: The R7 family of regulators of G protein signaling (RGS) proteins, comprising RGS6, RGS7, RGS9, and RGS11, regulate neuronal G protein signaling pathways. All members of the R7 RGS form trimeric complexes with the atypical G protein β subunit, Gβ5, and membrane anchor R7BP or R9AP. Association with Gβ5 and membrane anchors has been shown to be critical for maintaining proteolytic stability of the R7 RGS proteins. However, despite its functional importance, the mechanism of how R7 RGS forms complexes with Gβ5 and membrane anchors remains poorly understood. Here, we used protein-protein interaction, co-localization, and protein stability assays to show that association of RGS9 with membrane anchors requires Gβ5. We further establish that the recruitment of R7BP to the complex requires an intact interface between the N-terminal lobe of RGS9 and protein interaction surface of Gβ5. Site-directed mutational analysis reveals that distinct molecular determinants in the interface between Gβ5 and N-terminal Dishevelled, EGL-10, Pleckstrin/DEP Helical Extension (DEP/DHEY) domains are differentially involved in R7BP binding and proteolytic stabilization. On the basis of these findings, we conclude that Gβ5 contributes to the formation of the binding site to the membrane anchors and thus is playing a central role in the assembly of the proteolytically stable trimeric complex and its correct localization in the cell.
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Masuho
authors.forename: Hideko
authors.initials: H
authors.lastname: Wakasugi-Masuho
authors.forename: Ekaterina N
authors.initials: EN
authors.lastname: Posokhova
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Patton
authors.forename: Kirill A
authors.initials: KA
authors.lastname: Martemyanov
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D004252:DNA Mutational Analysis; D019281:Dimerization; D044387:GTP-Binding Protein beta Subunits / Q000737:chemistry*; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D020710:RGS Proteins / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D044387:GTP-Binding Protein beta Subunits; D020710:RGS Proteins; C116925:regulator of g-protein signaling 9