Mutagenesis and molecular modeling reveal the importance of the 5-HT3 receptor F-loop
| Autor: | Claire L. Padgett, Andrew J. Thompson, Sarah C. R. Lummis |
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| Rok vydání: | 2006 |
| Předmět: |
Models
Molecular Molecular model Mutant Molecular Sequence Data Mutagenesis (molecular biology technique) Biochemistry 5-HT3 receptor Cell Line Humans Homology modeling Amino Acid Sequence Receptor Molecular Biology Ion channel chemistry.chemical_classification Alanine Microscopy Confocal biology Sequence Homology Amino Acid Cell Biology Carbon Amino acid Protein Structure Tertiary Kinetics chemistry Mutation biology.protein Biophysics Mutagenesis Site-Directed Receptors Serotonin 5-HT3 |
| Zdroj: | The Journal of biological chemistry. 281(24) |
| ISSN: | 0021-9258 |
| Popis: | The 5-HT(3) receptor is a member of the Cys-loop family of ligand-gated ion channels. The extracellular domains of these proteins contain six amino acid loops (A-F) that converge to form the ligand binding site. In this study we have mutated 21 residues in or close to the 5-HT(3) receptor F-loop (Ile(192) to Gly(212)) to Ala or to a residue with similar chemical properties. Mutant receptors were expressed in HEK293 cells, and binding affinity was measured using [(3)H]granisetron. Two regions displayed decreases in binding affinity when mutated to Ala (Ile(192)-Arg(196) and Asp(204)-Ser(206)), but only one region was sensitive when mutated to chemically similar residues (Ile(192)-Val(201)). Homology modeling using acetylcholine-binding protein crystal structures with a variety of different bound ligands suggests there may be distinct movements of Trp(195) and Asp(204) upon ligand binding, indicating that these residues and their immediate neighbors have the ability to interact differently with different ligands. The models suggest predominantly lateral movement around Asp(204) and rotational movement around Trp(195), indicating the former is in a more flexible region. Overall our results are consistent with a flexible 5-HT(3) receptor F-loop with two regions that have specific but distinct roles in ligand binding. |
| Databáze: | OpenAIRE |
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