Separable binding sites for the natural agonist endothelin-1 and the non-peptide antagonist bosentan on human endothelin-A receptors
A three-dimensional model for the transmembrane domains of human endothelin-A receptor was built using structural information from bacteriorhodopsin and sequence alignment to other guanine-nucleotide-binding regulatory(G) protein-coupled receptors. Based on this model, 18 amino acids located at the...
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Veröffentlicht in: | European journal of biochemistry 1995-07, Vol.231 (1), p.266-270 |
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Sprache: | eng |
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Zusammenfassung: | A three-dimensional model for the transmembrane domains of human endothelin-A receptor was built using structural information from bacteriorhodopsin and sequence alignment to other guanine-nucleotide-binding regulatory(G) protein-coupled receptors. Based on this model, 18 amino acids located at the inside of the receptor were mutated and analyzed for binding of the natural ligand endothelin-1 and bosentan, a recently described potent orally active endothelin antagonist [Clozel, M., Breu, V., Gray, G., Kalina, B., Löffler, B.-M., Burri, K., Cassal, J.-M., Hirth, G., Müller, M., Neidhart, W. & Ramuz, H. (1994) Pharmacological characterization of bosentan, a new potent orally active nonpeptide endothelin receptor antagonist, J. Pharmacol. Exp. Ther. 270, 228-235]. Mutation of Gly97, Lys140, Lys159, Gln165 and Phe315, located in transmembrane region 1, 2, 3, 3, and 6, respectively, caused reduced specific binding of 125I-labelled endothelin-1, despite an expression level similar to wild-type endothelin-A receptor. Mutation of Tyr263, Arg326 and Asp351 preserved endothelin-1 binding but caused reduced binding of bosentan. These amino acids, located on transmembrane regions 5, 6 and 7, respectively, are conserved among endothelin-A and endothelin-B receptors but not in other G-protein-coupled receptors. These observations demonstrate a dissociation of the binding site for the peptidic natural agonist endothelin-1 and the synthetic non-peptide antagonist bosentan. They provide the molecular basis for bosentan being a specific antagonist for both, endothelin-A as well as endothelin-B receptors and may in combination with studies on structure/activity relationship support the design of novel and more potent endothelin receptor antagonists. |
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ISSN: | 0014-2956 1432-1033 |
DOI: | 10.1111/j.1432-1033.1995.tb20696.x |