G-protein coupled receptor which binds to the neurotransmitter dopamine with high affinity leading to the activation of an associated G-protein and downstream signaling pathways (PubMed:15378064, PubMed:16001968). Couples to G-proteins to inhibit adenylate cyclase (AC) activity and cAMP production (PubMed:15378064, PubMed:16001968). Antagonizes the D1-like dopamine receptor dop-1 to negatively regulate the rate of locomotion (PubMed:15378064). In GABAergic, RIC, and SIA neurons, antagonizes the function of dop-1 to play a role in behavioral plasticity and regulate the decision-making process when conflicting alternatives are present (PubMed:25536037). Antagonizes octopamine signaling in response to food by promoting the dopamine-mediated suppression of crh-1/CREB1 transcription factor activation in cholinergic SIA neurons (PubMed:19609300). This is most likely in association with the G(o)-alpha G-protein subunit goa-1 (PubMed:19609300). Promotes male mating behavior by antagonizing acetylcholine signaling to control the protrusion of copulatory spicules from the tail of males during hermaphrodite vulval location (PubMed:23166505). Expressed in the neurons of the head, ventral cord and tail with weak expression observed in body wall muscles and PVD neurons (PubMed:15378064). In the ventral cord, expressed strongly in GABAergic neurons with weaker expression in cholinergic motor neurons (PubMed:15378064). Expressed in cholinergic SIA neurons and octopaminergic RIC neurons (PubMed:19609300). In males, expressed in the dorsal and ventral spicule protractor and retractor muscles, and the sensory post-cloacal sensilla B (PCB) neuron (PubMed:23166505). Belongs to the G-protein coupled receptor 1 family.