title: Regulator of G Protein Signaling 7 (RGS7) Can Exist in a Homo-oligomeric Form That Is Regulated by Gαo and R7-binding Protein.
abstract: RGS (regulator of G protein signaling) proteins of the R7 subfamily (RGS6, -7, -9, and -11) are highly expressed in neurons where they regulate many physiological processes. R7 RGS proteins contain several distinct domains and form obligatory dimers with the atypical Gβ subunit, Gβ5 They also interact with other proteins such as R7-binding protein, R9-anchoring protein, and the orphan receptors GPR158 and GPR179. These interactions facilitate plasma membrane targeting and stability of R7 proteins and modulate their activity. Here, we investigated RGS7 complexes using in situ chemical cross-linking. We found that in mouse brain and transfected cells cross-linking causes formation of distinct RGS7 complexes. One of the products had the apparent molecular mass of ∼150 kDa on SDS-PAGE and did not contain Gβ5 Mass spectrometry analysis showed no other proteins to be present within the 150-kDa complex in the amount close to stoichiometric with RGS7. This finding suggested that RGS7 could form a homo-oligomer. Indeed, co-immunoprecipitation of differentially tagged RGS7 constructs, with or without chemical cross-linking, demonstrated RGS7 self-association. RGS7-RGS7 interaction required the DEP domain but not the RGS and DHEX domains or the Gβ5 subunit. Using transfected cells and knock-out mice, we demonstrated that R7-binding protein had a strong inhibitory effect on homo-oligomerization of RGS7. In contrast, our data indicated that GPR158 could bind to the RGS7 homo-oligomer without causing its dissociation. Co-expression of constitutively active Gαo prevented the RGS7-RGS7 interaction. These results reveal the existence of RGS protein homo-oligomers and show regulation of their assembly by R7 RGS-binding partners.
authors.affiliation: From the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136.
authors.forename: Junior
authors.initials: J
authors.lastname: Tayou
authors.affiliation: From the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: the Cole Eye Institute Cleveland Clinic, Cleveland, Ohio 44195, and.
authors.forename: Geeng-Fu
authors.initials: GF
authors.lastname: Jang
authors.affiliation: From the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136.
authors.forename: Alexey N
authors.initials: AN
authors.lastname: Pronin
authors.affiliation: the Department of Neuroscience, Scripps Research Institute, Jupiter, Florida 33458.
authors.forename: Cesare
authors.initials: C
authors.lastname: Orlandi
authors.affiliation: the Department of Neuroscience, Scripps Research Institute, Jupiter, Florida 33458.
authors.forename: Kirill A
authors.initials: KA
authors.lastname: Martemyanov
authors.affiliation: the Cole Eye Institute Cleveland Clinic, Cleveland, Ohio 44195, and.
authors.forename: John W
authors.initials: JW
authors.lastname: Crabb
authors.affiliation: From the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, VSlepak@med.miami.edu.
authors.forename: Vladlen Z
authors.initials: VZ
authors.lastname: Slepak
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D018345:Mice, Knockout; D055503:Protein Multimerization / Q000502:physiology*; D020710:RGS Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C499440:R7BP protein, mouse; D020710:RGS Proteins; C492039:RGS7 protein, human; C542323:RGS7BP protein, human; C492038:Rgs7 protein, mouse; D019206:GTP-Binding Protein alpha Subunits, Gi-Go
keywords: G protein; G protein-coupled receptor (GPCR); R7-binding protein (R7BP); immunoprecipitation; oligomer; protein cross-linking; regulator of G protein signaling (RGS); subcellular localization