Phosducin is a protein kinase A-regulated G-protein regulator. |
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Authors: | P H Bauer S Müller M Puzicha S Pippig B Obermaier E J Helmreich M J Lohse |
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Institution: | Laboratory of Molecular Biology, University of Munich, Max-Planck-Institute of Biochemistry, Martinsried, Germany. |
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Abstract: | Signal transduction by G-protein-coupled receptors is regulated by various mechanisms acting at the receptor level; those studied most thoroughly are from the beta-adrenergic receptor/Gs/adenylyl cyclase system. We report here a regulatory mechanism occurring at the level of the G proteins themselves. A protein with M(r) 33,000 that inhibits Gs-GTPase activity was purified from bovine brain. This protein is very similar or identical to phosducin, a protein previously thought to be specific for retina and pineal gland. Recombinant phosducin inhibited the GTPase activity of several G proteins, and also inhibited Gs-mediated adenylyl cyclase activation. Blockade of its inhibitory effects by protein kinase A suggests that phosducin may be part of a complex regulatory network controlling G-protein-mediated signalling. |
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