title: Phosphorylation and nuclear translocation of a regulator of G protein signaling (RGS10).
abstract: Heterotrimeric G proteins are involved in the transduction of hormonal and sensory signals across plasma membranes of eukaryotic cells. Hence, they are a critical point of control for a variety of agents that modulate cellular function. Activation of these proteins is dependent on GTP binding to their alpha (Galpha) subunits. Regulators of G protein signaling (RGS) bind specifically to activated Galpha proteins, potentiating the intrinsic GTPase activity of the Galpha proteins and thus expediting the termination of Galpha signaling. Although there are several points in most G protein controlled signaling pathways that are affected by reversible covalent modification, little evidence has been shown addressing whether or not the functions of RGS proteins are themselves regulated by such modifications. We report in this study the acute functional regulation of RGS10 thru the specific and inducible phosphorylation of RGS10 protein at serine 168 by cAMP-dependent kinase A. This phosphorylation nullifies the RGS10 activity at the plasma membrane, which controls the G protein-dependent activation of the inwardly rectifying potassium channel. Surprisingly, the phosphorylation-mediated attenuation of RGS10 activity was not manifested in an alteration of its ability to accelerate GTPase activity of Galpha. Rather, the phosphorylation event correlates with translocation of RGS10 from the plasma membrane and cytosol into the nucleus.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA. burgon@fas.harvard.edu
authors.forename: P G
authors.initials: PG
authors.lastname: Burgon
authors.forename: W L
authors.initials: WL
authors.lastname: Lee
authors.forename: A B
authors.initials: AB
authors.lastname: Nixon
authors.forename: E G
authors.initials: EG
authors.lastname: Peralta
authors.forename: P J
authors.initials: PJ
authors.lastname: Casey
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D003001:Cloning, Molecular; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D005260:Female; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D006801:Humans; D007700:Kinetics; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D015221:Potassium Channels / Q000502:physiology; D024661:Potassium Channels, Inwardly Rectifying; D021381:Protein Transport; D020710:RGS Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D043585:Receptor, Muscarinic M2; D011976:Receptors, Muscarinic / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012694:Serine; D014162:Transfection; D014982:Xenopus laevis
chemical_list: D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D020710:RGS Proteins; C101113:RGS10 protein, human; D043585:Receptor, Muscarinic M2; D011976:Receptors, Muscarinic; D011994:Recombinant Proteins; D005576:Colforsin; D012694:Serine; D017868:Cyclic AMP-Dependent Protein Kinases