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FASEB J. 1988 Oct;2(13):2841-8.

Receptor activation of G proteins.

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  • 1Department of Biochemistry, University of Massachusetts Medical School, Worcester 01655.


G proteins are a highly conserved family of membrane-associated proteins composed of alpha, beta, and gamma subunits. The alpha subunit, which is unique for each G protein, binds GDP or GTP. Receptors such as those for beta- and alpha-adrenergic catecholamines, muscarinic agonists, and the retinal photoreceptor rhodopsin, catalyze the exchange of GDP for GTP binding to the alpha subunit of a specific G protein. G alpha.GTP regulates appropriate effector enzymes such as adenylyl cyclase or the cyclic GMP phosphodiesterase. The beta gamma-subunit complex of G proteins is required for efficient receptor-catalyzed alpha subunit guanine nucleotide exchange and also functions as an attenuator of alpha subunit activation of effector enzymes. Recent elucidation of both receptor and G protein primary sequence has allowed structural predictions and new experimental approaches to study the mechanism of receptor-catalyzed G protein regulation of specific effector systems and the control of cell function including metabolism, secretion, and growth.

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