Gβ5 is required for the interaction of R7 RGS proteins with membrane anchors

The R7 subfamily of regulators of G protein signaling (RGS) proteins, comprised of 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 anchors, 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, the mechanism of how R7 RGS forms complexes with Gβ5 and membrane anchors remains poorly understood. Using protein‐protein interaction, co‐localization and protein stability assays, we found that association of R7 RGS proteins with membrane anchors requires Gβ5. Previous studies have established that the N‐terminal DEP domain of R7 RGS proteins makes direct contacts with Gβ5 and is also necessary for their binding to R7BP/R9AP. Accordingly, we found that point mutations in the DEP domain that disrupt its interaction with the Gβ5 prevent R7BP recruitment to the complex. We conclude that Gβ5 contributes to the formation of the binding site of R7BP, thus plays a central role in the assembly of the proteolytically stable trimeric complex and its correct localization in the cell.