Association with the Plasma Membrane Is Sufficient for Potentiating Catalytic Activity of Regulators of G Protein Signaling (RGS) Proteins of the R7 Subfamily.
Regulators of G protein Signaling (RGS) promote deactivation of heterotrimeric G proteins thus controlling the magnitude and kinetics of responses mediated by G protein-coupled receptors (GPCR). In the nervous system, RGS7 and RGS9-2 play essential role in vision, reward processing, and movement control. Both RGS7 and RGS9-2 belong to the R7 subfamily of RGS proteins that form macromolecular complexes with R7-binding protein (R7BP). R7BP targets RGS proteins to the plasma membrane and augments their GTPase-accelerating protein (GAP) activity, ultimately accelerating deactivation of G protein signaling. However, it remains unclear if R7BP serves exclusively as a membrane anchoring subunit or further modulates RGS proteins to increase their GAP activity. To directly answer this question, we utilized a rapidly reversible chemically induced protein dimerization system that enabled us to control RGS localization independent from R7BP in living cells. To monitor kinetics of Gα deactivation, we coupled this strategy with measuring changes in the GAP activity by bioluminescence resonance energy transfer-based assay in a cellular system containing μ-opioid receptor. This approach was used to correlate changes in RGS localization and activity in the presence or absence of R7BP. Strikingly, we observed that RGS activity is augmented by membrane recruitment, in an orientation independent manner with no additional contributions provided by R7BP. These findings argue that the association of R7 RGS proteins with the membrane environment provides a major direct contribution to modulation of their GAP activity.
['Muntean|Brian S|BS|', 'Martemyanov|Kirill A|KA|']
D000818:Animals D001681:Biological Assay D060807:Bioluminescence Resonance Energy Transfer Techniques D045744:Cell Line, Tumor D002462:Cell Membrane D005786:Gene Expression Regulation D017930:Genes, Reporter D008164:Luminescent Proteins D051379:Mice D009419:Nerve Tissue Proteins D009474:Neurons D055503:Protein Multimerization D020710:RGS Proteins D051381:Rats D017450:Receptors, Opioid, mu D015398:Signal Transduction D022021:Tacrolimus Binding Proteins
regulator of G protein signaling (RGS) G protein G protein-coupled receptor (GPCR) GTPase-activating protein (GAP) allosteric regulation signal transduction