The mouse 5-HT1C receptor contains eight hydrophobic domains and is X-linked

The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) exerts diverse physiological effects in the central and peripheral nervous systems and in smooth muscle by interacting with pharmacologically distinct membrane receptors. We report here the cDNA cloning of the mouse 5-HT1C receptor and its functional expression in Xenopus oocytes. This receptor possesses the unusual feature of containing eight hydrophobic domains capable of forming membrane-spanning alpha-helices, contrary to the usual '7-helix' paradigm for other membrane receptors that function through coupling to GTP-binding proteins. By hybridization analysis of Chinese hamster x mouse somatic cell hybrid lines, the gene for the receptor, designated Htr1c, has been assigned to the mouse X chromosome.