G protein-coupled receptor for 5-hydroxytryptamine (serotonin) (PubMed:14744596, PubMed:1513320, PubMed:1608964, PubMed:1733778, PubMed:21422162, PubMed:33762731). Also functions as a receptor for various alkaloids and psychoactive substances (PubMed:14744596, PubMed:1513320, PubMed:1608964, PubMed:1733778, PubMed:21422162, PubMed:33762731). Ligand binding causes a conformation change that triggers signaling via guanine nucleotide-binding proteins (G proteins) and modulates the activity of downstream effectors, such as adenylate cyclase (PubMed:14744596, PubMed:1513320, PubMed:1608964, PubMed:1733778, PubMed:21422162, PubMed:33762731). HTR1E is coupled to G(i)/G(o) G alpha proteins and mediates inhibitory neurotransmission by inhibiting adenylate cyclase activity (PubMed:33762731, PubMed:35610220). {ECO:0000269|PubMed:14744596, ECO:0000269|PubMed:1513320, ECO:0000269|PubMed:1608964, ECO:0000269|PubMed:1733778, ECO:0000269|PubMed:21422162, ECO:0000269|PubMed:33762731, ECO:0000269|PubMed:35610220}. This is the function of ENSG00000168830 (HTR1E, 5-hydroxytryptamine receptor 1E).