title: Three-dimensional models of alpha(2A)-adrenergic receptor complexes provide a structural explanation for ligand binding.
abstract: We have compared bacteriorhodopsin-based (alpha(2A)-AR(BR)) and rhodopsin-based (alpha(2A)-AR(R)) models of the human alpha(2A)-adrenengic receptor (alpha(2A)-AR) using both docking simulations and experimental receptor alkylation studies with chloroethylclonidine and 2-aminoethyl methanethiosulfonate hydrobromide. The results indicate that the alpha(2A)-AR(R) model provides a better explanation for ligand binding than does our alpha(2A)-AR(BR) model. Thus, we have made an extensive analysis of ligand binding to alpha(2A)-AR(R) and engineered mutant receptors using clonidine, para-aminoclonidine, oxymetazoline, 5-bromo-N-(4, 5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (UK14,304), and norepinephrine as ligands. The representative docked ligand conformation was chosen using extensive docking simulations coupled with the identification of favorable interaction sites for chemical groups in the receptor. These ligand-protein complex studies provide a rational explanation at the atomic level for the experimentally observed binding affinities of each of these ligands to the alpha(2A)-adrenergic receptor.
authors.affiliation: Department of Biochemistry and Pharmacy, Abo Akademi University and Turku Centre for Biotechnology, University of Turku and Abo Akademi University, Tykistökatu 6 A, FIN-20520 Turku, Finland. tiina.salminen@btk.utu.fi
authors.forename: T
authors.initials: T
authors.lastname: Salminen
authors.forename: M
authors.initials: M
authors.lastname: Varis
authors.forename: T
authors.initials: T
authors.lastname: Nyrönen
authors.forename: M
authors.initials: M
authors.lastname: Pihlavisto
authors.forename: A M
authors.initials: AM
authors.lastname: Hoffrén
authors.forename: T
authors.initials: T
authors.lastname: Lönnberg
authors.forename: A
authors.initials: A
authors.lastname: Marjamäki
authors.forename: H
authors.initials: H
authors.lastname: Frang
authors.forename: J M
authors.initials: JM
authors.lastname: Savola
authors.forename: M
authors.initials: M
authors.lastname: Scheinin
authors.forename: M S
authors.initials: MS
authors.lastname: Johnson
mesh_terms: D000818:Animals; D001436:Bacteriorhodopsins / Q000737:chemistry / Q000378:metabolism; D016466:CHO Cells; D006224:Cricetinae; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011487:Protein Conformation; D018341:Receptors, Adrenergic, alpha-2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C547768:ADRA2A protein, human; D008024:Ligands; D018341:Receptors, Adrenergic, alpha-2; D001436:Bacteriorhodopsins