A subclass of alpha-adrenergic receptors found on both presynaptic and postsynaptic membranes where they signal through Gi-Go G-proteins. While postsynaptic alpha-2 receptors play a traditional role in mediating the effects of adrenergic agonists, the subset of alpha-2 receptors found on presynaptic membranes signal the feedback inhibition of NEUROTRANSMITTER release.