Predicted to enable G protein-coupled serotonin receptor activity; neurotransmitter receptor activity; and serotonin binding activity. Predicted to be involved in G protein-coupled receptor signaling pathway, coupled to cyclic nucleotide second messenger; adenylate cyclase-inhibiting serotonin receptor signaling pathway; and chemical synaptic transmission. Predicted to act upstream of or within G protein-coupled receptor signaling pathway and regulation of appetite. Predicted to be located in endosome membrane. Predicted to be active in dendrite and plasma membrane. Is expressed in dorsal telencephalon. Orthologous to human HTR4 (5-hydroxytryptamine receptor 4).