The alpha-2-adrenergic receptor is a member of the G protein-coupled receptor superfamily. There are 3 highly homologous subtypes: alpha2A, alpha2B, and alpha2C. These receptors have a critical role in regulating neurotransmitter release from sympathetic nerves and from adrenergic neurons in the central nervous system. Alpha2C is required for normal presynaptic control of transmitter release from sympathetic nerves in the heart and from central noradrenergic neurons.
