G proteins are trimeric (alpha-beta-gamma) membrane-associated proteins that regulate flow of information from cell surface receptors to a variety of internal metabolic effectors. Interaction of a G protein with its activated receptor promotes exchange of GTP for GDP that is bound to the alpha subunit. The alpha-GTP complex dissociates from the beta-gamma heterodimer so that the subunits, in turn, may interact with and regulate effector molecules (Gilman, 1987 [PubMed 3113327]; summary by Ahmad et al., 1995) [PubMed 7606925].[supplied by OMIM, Nov 2010].