Definition of G–protein
: any of a class of cell membrane proteins that are coupled to cell surface receptors and upon stimulation of the receptor by an extracellular signaling molecule (as a hormone or neurotransmitter) bind to GTP to form an active complex which mediates an intracellular event (as activation of adenylate cyclase)
Origin and Etymology of g–protein
guanosine triphosphate-binding protein
First Known Use: 1967
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