Receptor for octopamine (OA) which is a neurotransmitter, neurohormone and neuromodulator in invertebrates (PubMed:9570796, PubMed:15816867). Stimulates intracellular accumulation of cAMP and Ca(2+) following ligand binding (PubMed:9570796, PubMed:15816867). Required for ovulation (PubMed:14623240, PubMed:19262750). Following activation on mature follicle cells by OA, induces activity of the metalloprotease Mmp2 which leads to breakdown of the posterior follicle wall, resulting in ovulation (PubMed:26473732). Ligand binding probably also leads to activation of CamKII which is also required for ovulation (PubMed:19262750). Modulates sleep/wake behavior by acting in neurons of the pars intercerebralis to promote wakefulness (PubMed:20223202). Plays a role in courtship conditioning where the courtship behavior of males rejected by already mated females is inhibited with further females (PubMed:23055498). Required in the mushroom body for appetitive olfactory learning (PubMed:23103875, PubMed:23345239). Specifically conveys the short-term reinforcing effects of sweet taste (PubMed:23103875, PubMed:25728694). In insulin-producing cells of the brain, plays a role in inhibiting transcription of insulin-like peptide Ilp3 (PubMed:24923784). Also plays a role in social behavior by modulating male agression (PubMed:24923784). Highly enriched in mushroom body neuropil and in the ellipsoid body (at protein level) (PubMed:9570796). Expressed in oviduct epithelium (at protein level) (PubMed:19262750). Expressed in the adult and larval brain, thoracic and abdominal ganglia, terminal cells of the larval tracheal system, muscle, mature eggs and reproductive system (PubMed:14623240, PubMed:25743690). Isoform C: Barely detectable in adult body but is expressed in adult head and third instar larva. Isoform B: Detected in adult head, adult body, pupa, third instar larva, 0-4 hour embryo, 0-18 hour embryo and 17-19 hour embryo with lowest expression observed in adult body and 17-19 hour embryo. Viable with no gross anatomical defects and females display normal courtship and copulation but are impaired in ovulation (PubMed:14623240). Many mature eggs are retained in the ovaries with mutant females laying significantly fewer eggs and taking much longer to ovulate an egg (PubMed:14623240, PubMed:26473732). Increased sleep with longer sleep bouts during the night and a greater number of sleep bouts during the day (PubMed:20223202). Severely impaired learning in appetitive olfactory conditioning which tests the capacity to learn and remember the odor associated with a sugar reward (PubMed:23345239). Belongs to the G-protein coupled receptor 1 family.