title: Differential interaction of GRK2 with members of the G alpha q family.
abstract: Regulators of G protein signaling (RGS) proteins bind to active G alpha subunits and accelerate the rate of GTP hydrolysis and/or block interaction with effector molecules, thereby decreasing signal duration and strength. RGS proteins are defined by the presence of a conserved 120-residue region termed the RGS domain. Recently, it was shown that the G protein-coupled receptor kinase 2 (GRK2) contains an RGS domain that binds to the active form of G alpha(q). Here, the ability of GRK2 to interact with other members of the G alpha(q) family, G alpha(11), G alpha(14), and G alpha(16), was tested. The signaling of all members of the G alpha(q) family, with the exception of G alpha(16), was inhibited by GRK2. Immunoprecipitation of full-length GRK2 or pull down of GST-GRK2-(45-178) resulted in the detection of G alpha(q), but not G alpha(16), in an activation-dependent manner. Moreover, activated G alpha(16) failed to promote plasma membrane (PM) recruitment of a GRK2-(45-178)-GFP fusion protein. Assays with chimeric G alpha(q)(-)(16) subunits indicated that the C-terminus of G alpha(q) mediates binding to GRK2. Despite showing no interaction with GRK2, G alpha(16) does interact with RGS2, in both inositol phosphate and PM recruitment assays. Thus, GRK2 is the first identified RGS protein that discriminates between members of the G alpha(q) family, while another RGS protein, RGS2, binds to both G alpha(q) and G alpha(16).
authors.affiliation: Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, 233 South 10th Street, Philadelphia, Pennsylvania 19107, USA.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Day
authors.forename: Christopher V
authors.initials: CV
authors.lastname: Carman
authors.forename: Rachel
authors.initials: R
authors.lastname: Sterne-Marr
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Benovic
authors.forename: Philip B
authors.initials: PB
authors.lastname: Wedegaertner
mesh_terms: D002460:Cell Line; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism* / Q000502:physiology; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D049452:Green Fluorescent Proteins; D020962:Heterotrimeric GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics; D005810:Multigene Family / Q000235:genetics; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000235:genetics; D021122:Protein Subunits / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D021381:Protein Transport / Q000235:genetics; D020710:RGS Proteins / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D014162:Transfection; D051552:beta-Adrenergic Receptor Kinases
chemical_list: D008164:Luminescent Proteins; D010446:Peptide Fragments; D021122:Protein Subunits; D020710:RGS Proteins; D011993:Recombinant Fusion Proteins; C105345:Rgs2 protein, mouse; D049452:Green Fluorescent Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; C112631:G protein alpha 16; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins