title: Stimulation of cAMP accumulation by the cloned Xenopus melatonin receptor through Gi and Gz proteins.
abstract: The Xenopus melatonin receptor was expressed in human embryonic kidney 293 cells and assayed for cAMP accumulation. In transfected 293 cells expressing the melatonin receptor, melatonin dose-dependently inhibited the endogenous adenylyl cyclases. In contrast, melatonin stimulated the accumulation of cAMP in cells co-expressing the type II adenylyl cyclase. Both the inhibitory and stimulatory responses to melatonin were mediated via Gi-like proteins as they were blocked by pertussis toxin. Upon co-transfection with the alpha subunit of Gz, the ability of melatonin to regulate both type II and the endogenous adenylyl cyclases became refractory to pertussis toxin, indicating that the melatonin receptor can also couple to Gz. However, other pertussis toxin-insensitive G proteins such as Gq, G12 and G13 were unable to interact with the melatonin receptor.
authors.affiliation: Department of Biology, Hong Kong University of Science and Technology, Kowloon.
authors.forename: L Y
authors.initials: LY
authors.lastname: Yung
authors.forename: S T
authors.initials: ST
authors.lastname: Tsim
authors.forename: Y H
authors.initials: YH
authors.lastname: Wong
mesh_terms: D037361:Adenylate Cyclase Toxin; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007668:Kidney; D008550:Melatonin / Q000494:pharmacology; D037342:Pertussis Toxin; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D044094:Receptors, Melatonin; D015398:Signal Transduction; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D014981:Xenopus
chemical_list: D037361:Adenylate Cyclase Toxin; D006063:Chorionic Gonadotropin; D018076:DNA, Complementary; D011956:Receptors, Cell Surface; D044094:Receptors, Melatonin; D010566:Virulence Factors, Bordetella; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D008550:Melatonin