Alpha-2 adrenergic receptors mediate the catecholamine-induced inhibition of adenylate cyclase through the action of G proteins. The Del322-325 variant has a significant loss of function. It is approximately 10 times more frequent in African-Americans compared with Caucasians (allele frequencies 0.381 versus 0.040). Belongs to the G-protein coupled receptor 1 family. Adrenergic receptor subfamily. ADRA2C sub-subfamily.