title: Crystal structures of the M1 and M4 muscarinic acetylcholine receptors.
abstract: Muscarinic M1-M5 acetylcholine receptors are G-protein-coupled receptors that regulate many vital functions of the central and peripheral nervous systems. In particular, the M1 and M4 receptor subtypes have emerged as attractive drug targets for treatments of neurological disorders, such as Alzheimer's disease and schizophrenia, but the high conservation of the acetylcholine-binding pocket has spurred current research into targeting allosteric sites on these receptors. Here we report the crystal structures of the M1 and M4 muscarinic receptors bound to the inverse agonist, tiotropium. Comparison of these structures with each other, as well as with the previously reported M2 and M3 receptor structures, reveals differences in the orthosteric and allosteric binding sites that contribute to a role in drug selectivity at this important receptor family. We also report identification of a cluster of residues that form a network linking the orthosteric and allosteric sites of the M4 receptor, which provides new insight into how allosteric modulation may be transmitted between the two spatially distinct domains.
authors.affiliation: Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Victoria, Australia.
authors.forename: David M
authors.initials: DM
authors.lastname: Thal
authors.affiliation: ConfometRx, 3070 Kenneth Street, Santa Clara, California 95054, USA.
authors.forename: Bingfa
authors.initials: B
authors.lastname: Sun
authors.affiliation: ConfometRx, 3070 Kenneth Street, Santa Clara, California 95054, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Feng
authors.affiliation: Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Victoria, Australia.
authors.forename: Vindhya
authors.initials: V
authors.lastname: Nawaratne
authors.affiliation: Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Victoria, Australia.
authors.forename: Katie
authors.initials: K
authors.lastname: Leach
authors.affiliation: Neuroscience, Eli Lilly, Indianapolis, Indiana 46285, USA.
authors.forename: Christian C
authors.initials: CC
authors.lastname: Felder
authors.affiliation: Computational Chemistry and Chemoinformatics, Eli Lilly, Indianapolis, Indiana 46285, USA.
authors.forename: Mark G
authors.initials: MG
authors.lastname: Bures
authors.affiliation: Computational Chemistry and Chemoinformatics, Eli Lilly, Sunninghill Road, Windlesham GU20 6PH, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Evans
authors.affiliation: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, USA.|Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: William I
authors.initials: WI
authors.lastname: Weis
authors.affiliation: ConfometRx, 3070 Kenneth Street, Santa Clara, California 95054, USA.
authors.forename: Priti
authors.initials: P
authors.lastname: Bachhawat
authors.affiliation: ConfometRx, 3070 Kenneth Street, Santa Clara, California 95054, USA.
authors.forename: Tong Sun
authors.initials: TS
authors.lastname: Kobilka
authors.affiliation: Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Victoria, Australia.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Sexton
authors.affiliation: ConfometRx, 3070 Kenneth Street, Santa Clara, California 95054, USA.|Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: Brian K
authors.initials: BK
authors.lastname: Kobilka
authors.affiliation: Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, 3052, Victoria, Australia.
authors.forename: Arthur
authors.initials: A
authors.lastname: Christopoulos
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000494:Allosteric Regulation / Q000187:drug effects; D000495:Allosteric Site / Q000187:drug effects; D000544:Alzheimer Disease; D003460:Crystallization; D018360:Crystallography, X-Ray; D054314:Drug Inverse Agonism; D006801:Humans; D008958:Models, Molecular; D009539:Nicotinic Acids / Q000378:metabolism / Q000494:pharmacology; D043643:Receptor, Muscarinic M1 / Q000737:chemistry* / Q000378:metabolism; D043588:Receptor, Muscarinic M4 / Q000737:chemistry* / Q000378:metabolism; D012559:Schizophrenia; D055672:Static Electricity; D013379:Substrate Specificity; D013499:Surface Properties; D013876:Thiophenes / Q000378:metabolism / Q000494:pharmacology; D000069447:Tiotropium Bromide / Q000494:pharmacology
chemical_list: C531529:3-amino-5-chloro-6-methoxy-4-methyl-thieno(2,3-b)pyridine-2-carboxylic acid cyclopropylamide; D009539:Nicotinic Acids; D043643:Receptor, Muscarinic M1; D043588:Receptor, Muscarinic M4; D013876:Thiophenes; D000109:Acetylcholine; D000069447:Tiotropium Bromide