Identification of a Gs activator region of the beta 2-adrenergic receptor that is autoregulated via protein kinase A-dependent phosphorylation.
We have localized a G protein activator region of the human beta 2-adrenergic receptor to region beta III-2 (from Arg259 to Lys273). The synthetic beta III-2, corresponding to the C-terminal end of the third cytoplasmic loop, activates Gs at nanomolar concentrations and weakly activates Gi. beta III-2 activates adenylyl cyclase at nanomolar concentrations in wild-type S49 lymphoma membranes, but not in membranes of unc mutant S49 cells, in which Gs is uncoupled from beta-adrenergic stimulation. Phosphorylation of beta III-2 by cAMP-dependent protein kinase A, which is involved in the desensitization of the beta-adrenergic receptor from Gs, drastically reduces the effect of beta III-2 on Gs while potentiating its action on Gi, resulting in a total loss of adenylyl cyclase-stimulating activity. These findings indicate that this receptor sequence is a multipotential G protein activator whose G protein specificity is regulated by protein kinase A.
Okamoto
T
T
Fourth Department of Internal Medicine, University of Tokyo School of Medicine, Japan.
Murayama
Y
Y
Hayashi
Y
Y
Inagaki
M
M
Ogata
E
E
Nishimoto
I
I
D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D010766:Phosphorylation; D011494:Protein Kinases / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D013329:Structure-Activity Relationship
D010455:Peptides; D011943:Receptors, Adrenergic, beta; D006160:Guanosine Triphosphate; D011494:Protein Kinases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D007545:Isoproterenol