ABSTRACT
The 2-adrenergic receptor (2AR) is a member of the G protein-coupled receptor (GPCR) family and is an important target for catecholamine hormones in physiological actions such as the relaxation of vascular and airway smooth muscle. Agonistbound 2ARs work principally by activating adenylyl cyclase through a coupled stimulatory heterotrimeric G protein (Gs), consisting of , , and subunits (1). Upon receptor activation, the G protein subunit binds guanosine triphosphate (GTP) and dissociates into G and G. G activates adenylyl cyclase, causing a rise in the intracellular levels of cyclic AMP, a second messenger that eventually mediates most downstream physiological effects. Signaling via G terminates when its intrinsic GTP hydrolysis stimulates the reassociation of the , , and subunits and recoupling to receptors (1).
