Heterotrimeric G Proteins

Heterotrimeric G proteins are cytosolic, membrane-associated proteins that transduce neuromodulatory signals within autonomic, sensory, and central nervous system neurons. Activated by G protein-coupled receptors embedded in the pre- and postsynaptic membranes of neurons, G proteins control the activities of ion channels and enzymes that generate intracellular second messenger molecules. The G. α and G. βγ components of heterotrimeric G proteins have both independent and tightly coordinated roles in the regulation of these effectors. G protein activation is controlled by G protein-coupled receptors and GTPase-activating proteins that respectively stimulate guanosine triphosphate binding and hydrolysis by Gα.