Phosducin inhibits receptor phosphorylation by the β‐adrenergic receptor kinase in a PKA‐regulated manner

Publisher Website
Google Scholar
Abstract
Homologous or receptor-specific desensitization of β-adrenergic receptors is thought to be triggered by receptor phosphorylation mediated by the β-adrenergic receptor kinases (ßARK). Upon receptor activation, cytosolic ßARK translocates to the membrane, probably by binding to G-protein βγ-subunits. Using the purified proteins reconstituted into phospholipid vesicles we show here that this binding process can be inhibited by phosducin, a cytosolic protein that has recently been described as a regulator of G-protein-mediated signalling. Phosducin appears to complete very effectively with ßARK for the G-protein βγ-subunits. These inhibitory effects of phosducin on receptor phosphorylation are antagonized following phosphorylation of phosducin by protein kinase A. It is proposed that phosducin may act as a regulator of homologous β-adrenergic receptor desensitization.