Enables G protein-coupled serotonin receptor activity and serotonin binding activity. Involved in several processes, including cellular response to temperature stimulus; negative regulation of serotonin secretion; and protein kinase C-activating G protein-coupled receptor signaling pathway. Acts upstream of or within adenylate cyclase-inhibiting G protein-coupled receptor signaling pathway; bone remodeling; and response to toxic substance. Located in cytoplasm; plasma membrane; and serotonergic synapse. Is integral component of presynaptic membrane. Part of G protein-coupled serotonin receptor complex. Is expressed in several structures, including alimentary system; central nervous system; eye; gonad; and immune system. Human ortholog(s) of this gene implicated in attention deficit hyperactivity disorder and conduct disorder. Orthologous to human HTR1B (5-hydroxytryptamine receptor 1B). [provided by Alliance of Genome Resources, Apr 2022]