Phosducin inhibits receptor phosphorylation by the beta-adrenergic receptor kinase in a PKA-regulated manner.
Homologous or receptor-specific desensitization of beta-adrenergic receptors is thought to be triggered by receptor phosphorylation mediated by the beta-adrenergic receptor kinases (beta ARK). Upon receptor activation, cytosolic beta ARK translocates to the membrane, probably by binding to G-protein beta gamma-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 beta ARK for the G-protein beta gamma-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 beta-adrenergic receptor desensitization.[1]References
- Phosducin inhibits receptor phosphorylation by the beta-adrenergic receptor kinase in a PKA-regulated manner. Hekman, M., Bauer, P.H., Söhlemann, P., Lohse, M.J. FEBS Lett. (1994) [Pubmed]
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