G protein beta gamma subunits

Guanine nucleotide binding (G) proteins relay extracellular signals encoded in light, small molecules, peptides, and proteins to activate or inhibit intracellular enzymes and ion channels. The larger G proteins, made up of G(alpha beta gamma) heterotrimers, dissociate into G(alpha) and G(beta gamma) subunits that separately activate intracellular effector molecules. Only recently has the G(beta gamma) subunit been recognized as a signal transduction molecule in its own right; G(beta gamma) is now known to directly regulate as many different protein targets as the G(alpha) subunit. Recent X-ray crystallography of G(alpha), G(beta gamma), and G(alpha beta gamma) subunits will guide the investigation of structure-function relationships.