title: Macromolecular composition dictates receptor and G protein selectivity of regulator of G protein signaling (RGS) 7 and 9-2 protein complexes in living cells.
abstract: Regulator of G protein signaling (RGS) proteins play essential roles in the regulation of signaling via G protein-coupled receptors (GPCRs). With hundreds of GPCRs and dozens of G proteins, it is important to understand how RGS regulates selective GPCR-G protein signaling. In neurons of the striatum, two RGS proteins, RGS7 and RGS9-2, regulate signaling by μ-opioid receptor (MOR) and dopamine D2 receptor (D2R) and are implicated in drug addiction, movement disorders, and nociception. Both proteins form trimeric complexes with the atypical G protein β subunit Gβ5 and a membrane anchor, R7BP. In this study, we examined GTPase-accelerating protein (GAP) activity as well as Gα and GPCR selectivity of RGS7 and RGS9-2 complexes in live cells using a bioluminescence resonance energy transfer-based assay that monitors dissociation of G protein subunits. We showed that RGS9-2/Gβ5 regulated both Gi and Go with a bias toward Go, but RGS7/Gβ5 could serve as a GAP only for Go. Interestingly, R7BP enhanced GAP activity of RGS7 and RGS9-2 toward Go and Gi and enabled RGS7 to regulate Gi signaling. Neither RGS7 nor RGS9-2 had any activity toward Gz, Gs, or Gq in the absence or presence of R7BP. We also observed no effect of GPCRs (MOR and D2R) on the G protein bias of R7 RGS proteins. However, the GAP activity of RGS9-2 showed a strong receptor preference for D2R over MOR. Finally, RGS7 displayed an four times greater GAP activity relative to RGS9-2. These findings illustrate the principles involved in establishing G protein and GPCR selectivity of striatal RGS proteins.
authors.affiliation: From the Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, Florida 33410.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Masuho
authors.affiliation: From the Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, Florida 33410.
authors.forename: Keqiang
authors.initials: K
authors.lastname: Xie
authors.affiliation: From the Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, Florida 33410. Electronic address: kirill@scripps.edu.
authors.forename: Kirill A
authors.initials: KA
authors.lastname: Martemyanov
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003342:Corpus Striatum / Q000166:cytology / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D020710:RGS Proteins / Q000235:genetics / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins; D020710:RGS Proteins; C492039:RGS7 protein, human; C542323:RGS7BP protein, human; D017448:Receptors, Dopamine D2; D017450:Receptors, Opioid, mu; C116925:regulator of g-protein signaling 9; D019206:GTP-Binding Protein alpha Subunits, Gi-Go
keywords: G Protein-coupled Receptors (GPCR); G Proteins; Neurons; RGS Proteins; Signal Transduction