Differential desensitization and phosphorylation of three cloned and transfected alpha 2-adrenergic receptor subtypes.

摘要: Genes encoding 3 distinct subtypes of human alpha 2-adrenergic receptor are known and found, respectively, on chromosome 10, 4, 2 (alpha 2-C10, 2-C4, 2-C2 adrenergic receptors). All receptors inhibit adenylyl cyclase via Gi proteins. To study compare their regulatory properties we assessed the ability each to undergo agonist-promoted desensitization phosphorylation. When Chinese hamster ovary cells stably expressing three genes were incubated with epinephrine for 20 min, a marked decrease in sensitivity subsequent agonist-mediated inhibition was observed 2-C10 but not 2-C4 receptors. similar incubations performed 32Pi-labeled immunoprecipitated specific antibodies, found an approximately 3-fold increase phosphorylation after exposure. transfected into COS also stimulated while having only slight effect Cotransfection cDNA beta-adrenergic kinase further increased little or no Moreover purified reconstituted recombinant could be phosphorylated agonist-dependent fashion whereas not. These observations suggest subtype-specific differences susceptibility desensitization.