Functional desensitization of the isolated beta-adrenergic receptor by the beta-adrenergic receptor kinase: potential role of an analog of the retinal protein arrestin (48-kDa protein).
The beta-adrenergic receptor kinase is an enzyme, possibly analogous to rhodopsin kinase, that multiply phosphorylates the beta-adrenergic receptor only when it is occupied by stimulatory agonists. Since this kinase may play an important role in mediating the process of homologous, or agonist-specific, desensitization, we investigated the functional consequences of receptor phosphorylation by the kinase and possible analogies with the mechanism of action of rhodopsin kinase. Pure hamster lung beta 2-adrenergic receptor, reconstituted in phospholipid vesicles, was assessed for its ability to mediate agonist-promoted stimulation of the GTPase activity of coreconstituted stimulatory guanine nucleotide-binding regulatory protein. When the receptor was phosphorylated by partially (approximately 350-fold) purified preparations of beta-adrenergic receptor kinase, as much as 80% inactivation of its functional activity was observed. However, the use of more highly purified enzyme preparations led to a dramatic decrease in the ability of phosphorylation to inactivate the receptor such that pure enzyme preparations (approximately 20,000-fold purified) caused only minimal (approximately 1off/- 7%) inactivation. Addition of pure retinal arrestin (48-kDa protein or S antigen), which is involved in enhancing the inactivating effect of rhodopsin phosphorylation by rhodopsin kinase, led to partial restoration of the functional effect of beta-adrenergic receptor kinase-promoted phosphorylation (41 +/- 3% inactivation). These results suggest the possibility that a protein analogous to retinal arrestin may exist in other tissues and function in concert with beta-adrenergic receptor kinase to regulate the activity of adenylate cyclase-coupled receptors.
Benovic
J L
JL
Department of Medicine (Cardiology), Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710.
Kühn
H
H
Weyand
I
I
Codina
J
J
Caron
M G
MG
Lefkowitz
R J
RJ
D000818:Animals; D000941:Antigens / Q000378:metabolism*; D019393:Arrestin; D017868:Cyclic AMP-Dependent Protein Kinases; D005136:Eye Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D012160:Retina / Q000502:physiology; D051552:beta-Adrenergic Receptor Kinases
D000941:Antigens; D019393:Arrestin; D005136:Eye Proteins; D010750:Phosphoproteins; D011943:Receptors, Adrenergic, beta; D011494:Protein Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; D019204:GTP-Binding Proteins