Enables dopamine neurotransmitter receptor activity, coupled via Gi/Go. Involved in regulation of circadian rhythm and regulation of postsynaptic neurotransmitter receptor internalization. Acts upstream of or within several processes, including adenylate cyclase-inhibiting dopamine receptor signaling pathway; behavioral response to cocaine; and inhibitory postsynaptic potential. Is active in glutamatergic synapse. Is expressed in several structures, including alimentary system; central nervous system; hemolymphoid system gland; integumental system; and reproductive system. Human ortholog(s) of this gene implicated in several diseases, including Gilles de la Tourette syndrome; antisocial personality disorder; attention deficit hyperactivity disorder; conduct disorder; and dyslexia. Orthologous to human DRD4 (dopamine receptor D4). [provided by Alliance of Genome Resources, Apr 2022]