The alpha-2A adrenergic receptor (ñ<sub>2A</sub> adrenoceptor), also known as ADRA2A, is an ñ<sub>2</sub>-adrenergic receptor, and also denotes the human gene encoding it.
ñ<sub>2</sub>-adrenergic receptors include 3 highly homologous subtypes: ñ<sub>2A</sub>, ñ<sub>2B</sub>, and ñ<sub>2C</sub>. These receptors have a critical role in regulating neurotransmitter release from sympathetic nerves and from adrenergic neurons in the central nervous system. Studies in mice revealed that both the ñ<sub>2A</sub> and ñ<sub>2C</sub> subtypes were required for normal presynaptic control of transmitter release from sympathetic nerves in the heart and from central noradrenergic neurons; the ñ<sub>2A</sub> subtype inhibited transmitter release at high stimulation frequencies, whereas the ñ<sub>2C</sub> subtype modulated neurotransmission at lower levels of nerve activity.
This gene encodes ñ<sub>2A</sub> subtype and it contains no introns in either its coding or untranslated sequences.