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Structural features of the ligand-binding domain of the serotonin 5HT3 receptor
Journal article   Open access   Peer reviewed

Structural features of the ligand-binding domain of the serotonin 5HT3 receptor

D Yan, M K Schulte, K E Bloom and M M White
The Journal of biological chemistry, v 274(9), pp 5537-5541
26 Feb 1999
DOI: https://doi.org/10.1074/jbc.274.9.5537
PMID: 10026168
Featured in Collection :   UN Sustainable Development Goals @ Drexel
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https://doi.org/10.1074/jbc.274.9.5537View
Published, Version of Record (VoR)CC BY V4.0,  Open

Abstract

Amino Acid Sequence Receptors, Serotonin, 5-HT3 Mutagenesis, Site-Directed Protein Structure, Secondary Base Sequence Humans Ligands Receptors, Serotonin - chemistry Receptors, Serotonin - genetics Binding Sites Receptors, Serotonin - metabolism DNA, Complementary
The nicotinic acetylcholine receptor (AChR) and the serotonin type 3 receptor (5HT3R) are members of the ligand-gated ion channel gene family. Both receptors are inhibited by nanomolar concentrations of d-tubocurarine (curare) in a competitive fashion. Chemical labeling studies on the AChR have identified tryptophan residues on the gamma (gammaTrp-55) and delta (deltaTrp-57) subunits that interact with curare. Comparison of the sequences of these two subunits with the 5HT3R shows that a tryptophan residue is found in the homologous position in the 5HT3R (Trp-89), suggesting that this residue may be involved in curare-5HT3R interactions. Site-directed mutagenesis at position Trp-89 markedly reduces the affinity of the 5HT3R for the antagonists curare and granisetron but has little effect on the affinity for the agonist serotonin. To further examine the role of this region of the receptor in ligand-receptor interactions, alanine-scanning mutagenesis analysis of the region centered on Trp-89 (Thr-85 to Trp-94) was carried out, and the ligand binding properties of the mutant receptors were determined. Within this region of the receptor, curare affinity is reduced by substitution only at Trp-89, whereas serotonin affinity is reduced only by substitution at Arg-91. On the other hand, granisetron affinity is reduced by substitutions at Trp-89, Arg-91, and Tyr-93. This differential effect of substitutions on ligand affinity suggests that different ligands may have different points of interaction within the ligand-binding pocket. In addition, the every-other-residue periodicity of the effects on granisetron affinity strongly suggests that this region of the ligand-binding site of the 5HT3R (and by inference, other members of the ligand-gated ion channel family) is in a beta-strand conformation.

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Web of Science research areas
Biochemistry & Molecular Biology
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