title: Src-mediated RGS16 tyrosine phosphorylation promotes RGS16 stability.
abstract: The amplitude of signaling evoked by stimulation of G protein-coupled receptors may be controlled in part by the GTPase accelerating activity of the regulator of G protein signaling (RGS) proteins. In turn, subcellular targeting, protein-protein interactions, or post-translational modifications such as phosphorylation may shape RGS activity and specificity. We found previously that RGS16 undergoes tyrosine phosphorylation on conserved tyrosine residues in the RGS box. Phosphorylation on Tyr(168) was mediated by the epidermal growth factor receptor (EGFR). We show here that endogenous RGS16 is phosphorylated after epidermal growth factor stimulation of MCF-7 cells. In addition, p60-Src or Lyn kinase phosphorylated recombinant RGS16 in vitro, and RGS16 underwent phosphorylation in the presence of constitutively active Src (Y529F) in EGFR(-) CHO-K1 cells. Blockade of endogenous Src activity by selective inhibitors attenuated RGS16 phosphorylation induced by pervanadate or receptor stimulation. Furthermore, the rate of RGS16 degradation was reduced in cells expressing active Src or treated with pervanadate or a G protein-coupled receptor ligand (CXCL12). Induction of RGS16 tyrosine phosphorylation was associated with increased RGS16 protein levels and enhanced GAP activity in cell membranes. These results suggest that Src mediates RGS16 tyrosine phosphorylation, which may promote RGS16 stability.
authors.affiliation: Laboratory of Allergic Diseases, NIAID/National Institutes of Health, 12441 Parklawn Drive, Rockville, MD 20852, USA.
authors.forename: Alexandrine
authors.initials: A
authors.lastname: Derrien
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
authors.forename: James L
authors.initials: JL
authors.lastname: Osterhout
authors.forename: Yong-Chao
authors.initials: YC
authors.lastname: Ma
authors.forename: Graeme
authors.initials: G
authors.lastname: Milligan
authors.forename: Marilyn G
authors.initials: MG
authors.lastname: Farquhar
authors.forename: Kirk M
authors.initials: KM
authors.lastname: Druey
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D020710:RGS Proteins / Q000737:chemistry* / Q000378:metabolism*; D051552:beta-Adrenergic Receptor Kinases; D019061:src-Family Kinases / Q000502:physiology*
chemical_list: D020690:GTPase-Activating Proteins; D011506:Proteins; D020710:RGS Proteins; C107413:RGS16 protein; D019061:src-Family Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases