Cloning and expression of a 5HT7 receptor from Xenopus laevis

A clone encoding a 5TH7 receptor, XM2, has been isolated from Xenopus laevis. The mRNA encoding XM2 is expressed in brain, liver, muscle, kidney, intestine and skin, but not in heart or lung. Co-expression of XM2 and the cystic fibrosis transmembrane conductance regulator (CFTR) in Xenopus oocytes demonstrated coupling of the receptor and the channel via the protein kinase A pathway. A rank order of potency was obtained for serotonergic agonists of 5-hydroxytryptamine (5HT) > or = 5-methoxytryptamine (5MeOxyT) > or = alpha-methyl-5-hydroxytryptamine (alpha Me5HT) > 8-OH-DPAT, and for serotonergic antagonists of ritanserin > NAN190 > mesulergine not equal to pindolol. Thus, XM2 encodes a 5HT receptor with sequence homology to mammalian 5HT7 receptors, a similar intracellular signal transduction and receptor pharmacology, but a broader distribution in peripheral tissues.