This is one of the several different receptors for 5-hydroxytryptamine (serotonin), a biogenic hormone that functions as a neurotransmitter, a hormone, and a mitogen. The activity of this receptor is mediated by G proteins that stimulate adenylate cyclase. May interact with PATJ, MAGI2, MPP3, NOS1, SLC9A3R1, SEC23A and SNX27. May form a complex including SLC9A3R1 and EZR (By similarity). Interaction with SNX27 mediates recruitment to early endosomes, while interaction with SLC9A3R1 and EZR might target the protein to specialized subcellular regions, such as microvilli. Interacts (via C-terminus) with GRK5; this interaction is promoted by 5-HT (serotonin). Belongs to the G-protein coupled receptor 1 family.