Abstract
Homologous or agonist-specific desensitization of beta-adrenergic
receptors is thought to be mediated by a specific kinase, the beta-adrenergic
receptor kinase (beta ARK). However, recent data suggest that a cofactor
is required for this kinase to inhibit receptor function. The complementary
DNA for such a cofactor was cloned and found to encode a 418-amino
acid protein homologous to the retinal protein arrestin. The protein,
termed beta-arrestin, was expressed and partially purified. It inhibited
the signaling function of beta ARK-phosphorylated beta-adrenergic
receptors by more than 75 percent, but not that of rhodopsin. It
is proposed that beta-arrestin in concert with beta ARK effects homologous
desensitization of beta-adrenergic receptors.
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