title: Molecular modeling of the M3 acetylcholine muscarinic receptor and its binding site.
abstract: The present study reports the results of a combined computational and site mutagenesis study designed to provide new insights into the orthosteric binding site of the human M3 muscarinic acetylcholine receptor. For this purpose a three-dimensional structure of the receptor at atomic resolution was built by homology modeling, using the crystallographic structure of bovine rhodopsin as a template. Then, the antagonist N-methylscopolamine was docked in the model and subsequently embedded in a lipid bilayer for its refinement using molecular dynamics simulations. Two different lipid bilayer compositions were studied: one component palmitoyl-oleyl phosphatidylcholine (POPC) and two-component palmitoyl-oleyl phosphatidylcholine/palmitoyl-oleyl phosphatidylserine (POPC-POPS). Analysis of the results suggested that residues F222 and T235 may contribute to the ligand-receptor recognition. Accordingly, alanine mutants at positions 222 and 235 were constructed, expressed, and their binding properties determined. The results confirmed the role of these residues in modulating the binding affinity of the ligand.
authors.affiliation: Centre de Biotecnologia Molecular, Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, 08028 Barcelona, Spain.
authors.forename: Marlet
authors.initials: M
authors.lastname: Martinez-Archundia
authors.forename: Arnau
authors.initials: A
authors.lastname: Cordomi
authors.forename: Pere
authors.initials: P
authors.lastname: Garriga
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Perez
mesh_terms: D000409:Alanine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011485:Protein Binding; D043587:Receptor, Muscarinic M3 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012243:Rhodopsin / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D043587:Receptor, Muscarinic M3; D012243:Rhodopsin; D000409:Alanine