title: Pharmacology and structure of isolated conformations of the adenosine A₂A receptor define ligand efficacy.
abstract: Using isolated receptor conformations crystal structures of the adenosine A₂A receptor have been solved in active and inactive states. Studying the change in affinity of ligands at these conformations allowed qualitative prediction of compound efficacy in vitro in a system-independent manner. Agonist 5'-N-ethylcarboxamidoadenosine displayed a clear preference to bind to the active state receptor; inverse agonists (xanthine amine congener, ZM241385, SCH58261, and preladenant) bound preferentially to the inactive state, whereas neutral antagonists (theophylline, caffeine, and istradefylline) demonstrated equal affinity for active and inactive states. Ligand docking into the known crystal structures of the A₂A receptor rationalized the pharmacology observed; inverse agonists, unlike neutral antagonists, cannot be accommodated within the agonist-binding site of the receptor. The availability of isolated receptor conformations opens the door to the concept of "reverse pharmacology" whereby the functional pharmacology of ligands can be characterized in a system-independent manner by their affinity for a pair (or set) of G protein-coupled receptor conformations.
authors: Heptares Therapeutics Ltd, Welwyn Garden City, Hertfordshire, United Kingdom.
authors: Kirstie A
authors: KA
authors: Bennett
authors: Benjamin
authors: B
authors: Tehan
authors: Guillaume
authors: G
authors: Lebon
authors: Christopher G
authors: CG
authors: Tate
authors: Malcolm
authors: M
authors: Weir
authors: Fiona H
authors: FH
authors: Marshall
authors: Christopher J
authors: CJ
authors: Langmead
mesh_terms: D058908:Adenosine A2 Receptor Agonists / Q000494:pharmacology*; D058917:Adenosine A2 Receptor Antagonists / Q000494:pharmacology*; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D008024:Ligands; D008968:Molecular Conformation; D043705:Receptor, Adenosine A2A / Q000737:chemistry* / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D058908:Adenosine A2 Receptor Agonists; D058917:Adenosine A2 Receptor Antagonists; D008024:Ligands; D043705:Receptor, Adenosine A2A; D043562:Receptors, G-Protein-Coupled