Cloning and pharmacological characterization of a novel human 5-hydroxytryptamine1D receptor subtype.
The canine RDC4 gene was used to isolate two distinct human serotonin receptor genes. The receptor encoded by clone RH-6 was the species homolog of RDC4 and was identical to a human serotonin 5-hydroxytryptamine1D (5-HT1D) receptor that was recently reported [Mol. Pharmacol. 40:143-148 (1991)]. The receptor encoded by RH-2 was a novel 5-HT receptor that was 61% identical to RH-6 and showed the greatest homology with the rat 5-HT1B receptor sequence (94%). The RH-2 gene contained an intronless, 1170-base pair, open reading frame that encoded a 390-amino acid protein that contained all of the hallmarks of a guanine nucleotide-binding protein-linked receptor. Heterologous expression of the RH-2 gene in Chinese hamster ovary cells led to the appearance of high affinity binding sites for 5-HT (Kd = 2.6 nM, Bmax = 2.9 pmol/mg of membrane protein), and the receptor expressed in Chinese hamster ovary cells was coupled to inhibition of adenylyl cyclase. Competition binding experiments using compounds that are selective for various 5-HT receptor subtypes showed the highest correlation with a 5-HT1D-like receptor (r = 0.89) and a low correlation with 5-HT1B-like receptors. Examples of the 5-HT1D-like pharmacology displayed by RH-2 include high affinity for the 5-HT1D-selective compound sumatriptan (Ki = 9.4 nM) and for the alpha 2-adrenergic receptor antagonist rauwolscine (Ki = 47 nM). Therefore, despite the close genetic relationship between RH-2 and the rat 5-HT1B receptor, our results indicate that the receptor encoded by RH-2 2 is best classified as a human 5-HT1D receptor subtype and defines a second member of the human 5-HT1D receptor family.
Veldman
S A
SA
Department of Cell Biology, Upjohn Laboratories, Kalamazoo, Michigan 49007.
Bienkowski
M J
MJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D016466:CHO Cells / Q000502:physiology; D003001:Cloning, Molecular; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D015342:DNA Probes; D004285:Dogs; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D011863:Radioimmunoassay; D011985:Receptors, Serotonin / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D017385:Sequence Homology; D012701:Serotonin / Q000494:pharmacology; D014162:Transfection
D015342:DNA Probes; D011985:Receptors, Serotonin; D005576:Colforsin; D012701:Serotonin; D000242:Cyclic AMP; D019204:GTP-Binding Proteins