title: Nicotinic agonist binding site mapped by methionine- and tyrosine-scanning coupled with azidochloropyridinyl photoaffinity labeling.
abstract: Agonists activating nicotinic acetylcholine receptors (nAChR) include potential therapeutic agents and also toxicants such as epibatidine and neonicotinoid insecticides with a chloropyridinyl substituent. Nicotinic agonist interactions with mollusk (Aplysia californica) acetylcholine binding protein, a soluble surrogate of the nAChR extracellular domain, are precisely defined by scanning with 17 methionine and tyrosine mutants within the binding site by photoaffinity labeling with 5-azido-6-chloropyridin-3-yl probes that have similar affinities to their nonazido counterparts. Methionine and tyrosine are the only residues found derivatized, and their reactivity exquisitely depends on the direction of the azido moiety and its apposition to the reactive amino acid side chains.
authors.affiliation: Environmental Chemistry and Toxicology Laboratory, Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720-3112, USA.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Tomizawa
authors.forename: Todd T
authors.initials: TT
authors.lastname: Talley
authors.forename: John F
authors.initials: JF
authors.lastname: Park
authors.forename: David
authors.initials: D
authors.lastname: Maltby
authors.forename: Katalin F
authors.initials: KF
authors.lastname: Medzihradszky
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Durkin
authors.forename: Jose M
authors.initials: JM
authors.lastname: Cornejo-Bravo
authors.forename: Alma L
authors.initials: AL
authors.lastname: Burlingame
authors.forename: John E
authors.initials: JE
authors.lastname: Casida
authors.forename: Palmer
authors.initials: P
authors.lastname: Taylor
mesh_terms: D000818:Animals; D001048:Aplysia / Q000737:chemistry; D001386:Azides / Q000032:analysis* / Q000737:chemistry; D001665:Binding Sites; D003198:Computer Simulation; D013058:Mass Spectrometry; D008715:Methionine / Q000737:chemistry* / Q000378:metabolism*; D008956:Models, Chemical; D015394:Molecular Structure; D019920:Photoaffinity Labels / Q000032:analysis* / Q000737:chemistry; D011725:Pyridines / Q000032:analysis* / Q000737:chemistry; D011978:Receptors, Nicotinic / Q000737:chemistry* / Q000378:metabolism*; D014443:Tyrosine / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001386:Azides; D019920:Photoaffinity Labels; D011725:Pyridines; D011978:Receptors, Nicotinic; D014443:Tyrosine; D008715:Methionine