EXPRESSION CLONING OF A HIGH-AFFINITY MELATONIN RECEPTOR FROM XENOPUSDERMAL MELANOPHORES

Citation
T. Ebisawa et al., EXPRESSION CLONING OF A HIGH-AFFINITY MELATONIN RECEPTOR FROM XENOPUSDERMAL MELANOPHORES, Proceedings of the National Academy of Sciences of the United Statesof America, 91(13), 1994, pp. 6133-6137
Citations number
35
Categorie Soggetti
Multidisciplinary Sciences
ISSN journal
00278424
Volume
91
Issue
13
Year of publication
1994
Pages
6133 - 6137
Database
ISI
SICI code
0027-8424(1994)91:13<6133:ECOAHM>2.0.ZU;2-U
Abstract
Using an expression cloning strategy, a high-affinity melatonin recept or cDNA has been isolated from Xenopus laevis dermal melanophores. Tra nsient expression of the cDNA in COS-7 cells resulted in high-affinity 2-[I-125]- iodomelatonin binding (K-d = 6.3 +/- 0.3 X 10(-11) M). In addition, six ligands exhibited a rank order of inhibition of specific 2-[I-125] iodomelatonin binding that was identical to that reported f or endogenous high-affinity receptors. Functional studies of CHO cells stably expressing the receptor cDNA showed that melatonin acting thro ugh the cloned receptor inhibited forskolin-stimulated cAMP accumulati on in a dose-dependent manner. Northern blot analysis showed that mela tonin receptor transcripts are moderately expressed in Xenopus dermal melanophores. The cDNA encodes a protein of 420 amino acids, which con tains seven hydrophobic segments. Structural analysis revealed that th e receptor protein is a newly discovered member of the guanine nucleot ide binding protein-coupled receptor family.