The β-Adrenergic Receptor Is a Substrate for the Insulin Receptor Tyrosine Kinase (∗)

• Published in: The Journal of biological chemistry 1996-01, Vol.271 (2), p.1061-1064
• Main Authors: Baltensperger, Kurt, Karoor, Vijaya, Paul, Hyacinth, Ruoho, Arnold, Czech, Michael P., Malbon, Craig C.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; CHO Cells; Cricetinae; GTP-Binding Proteins - metabolism; Humans; Molecular Sequence Data; Phosphorylation; Receptor Protein-Tyrosine Kinases - metabolism; Receptor, IGF Type 1 - metabolism; Receptor, Insulin - metabolism; Receptors, Adrenergic, beta-2 - metabolism; Recombinant Proteins - metabolism; Substrate Specificity
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.271.2.1061

G-protein-linked receptors and intrinsic tyrosine-kinase growth receptors represent two prominent modalities in cell signaling. Cross-regulation among members of both receptor superfamilies has been reported, including the counter-regulatory effects of insulin on β-adrenergic catecholamine action. Cells stimulated by insulin show loss of function and increased phosphotyrosine content of β2-adrenergic receptors. Phosphorylation of tyrosyl residues 350/354 of β2-adrenergic receptors is obligatory for counter-regulation by insulin (Karoor, V., Baltensperger, K., Paul, H., Czech, M., and Malbon, C. C.(1995) J. Biol. Chem. 270, 25305-25308), suggesting the hypothesis that G-protein-linked receptors themselves may act as substrates for the insulin receptor and other growth factor receptors. This hypothesis was evaluated directly using recombinant human insulin receptor, hamster β2-adrenergic receptor, and an in vitro reconstitution and phosphorylation assay. Insulin is shown to stimulate insulin receptor-catalyzed phosphorylation of the β2-adrenergic receptor. Phosphoamino acid analysis establishes that insulin receptor-catalyzed phosphorylation of the β2-adrenergic receptor in vitro is confined to phosphotyrosine. High pressure liquid chromatography and two-dimensional mapping reveal insulin receptor-catalyzed phosphorylation of the β2-adrenergic receptor at residues Tyr132/Tyr141, Tyr350/Tyr354, and Tyr364, known sites of phosphorylation in response to insulin in vivo. Insulin-like growth factor-I receptor as well as the insulin receptor displays the capacity to phosphorylate the β2-adrenergic receptor in vitro, establishing a new paradigm, i.e. G-protein-linked receptors acting as substrates for intrinsic tyrosine kinase growth factor receptors.