Two Amino Acid Differences in the Sixth Transmembrane Domain Are Partially Responsible for the Pharmacological Differences Between the 5-HT1Dβ and 5-HT1E 5-Hydroxytryptamine Receptors |
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Authors: | Eric M Parker Darcy G Izzarelli Lore Lewis-Higgins Dawn Palmer Robert A Shapiro |
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Institution: | Department of CNS Biology, Bristol-Myers Squibb Company, Wallingford, Connecticut;and; Department of Inflammation, Bristol-Myers Squibb Company, Seattle, Washington, U.S.A. |
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Abstract: | Abstract: 5-Hydroxytryptamine elicits its physiological effects by interacting with a diverse group of receptors. Two of these receptors, the 5-HT1Dβ and the 5-HT1E receptors, are ∼60% identical in the transmembrane domains that presumably form the ligand binding site yet have very different pharmacological properties. Analysis of the pharmacological properties of a series of chimeric 5-HT1Dβ/5-HT1E receptors indicates that sequences in the sixth and seventh transmembrane domains are responsible for the differential affinity of 5-carboxamidotryptamine for these two receptors. More detailed analysis shows that two amino acid differences in the sixth transmembrane domain (Ile333 and Ser334 in the 5-HT1Dβ receptor, corresponding to Lys310 and Glu311 in the 5-HT1E receptor) are largely responsible for the differential affinities of some, but not all, ligands for the 5-HT1Dβ and 5-HT1E receptors. It is likely that these two amino acids subtly determine the overall three-dimensional structure of the receptor rather than interact directly with individual ligands. |
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Keywords: | 5-Hydroxytryptamine Serotonin Receptor 5-HT1D receptor 5-HT1E receptor Mutagenesis |
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