title: The 2.6 angstrom crystal structure of a human A2A adenosine receptor bound to an antagonist.
abstract: The adenosine class of heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) mediates the important role of extracellular adenosine in many physiological processes and is antagonized by caffeine. We have determined the crystal structure of the human A2A adenosine receptor, in complex with a high-affinity subtype-selective antagonist, ZM241385, to 2.6 angstrom resolution. Four disulfide bridges in the extracellular domain, combined with a subtle repacking of the transmembrane helices relative to the adrenergic and rhodopsin receptor structures, define a pocket distinct from that of other structurally determined GPCRs. The arrangement allows for the binding of the antagonist in an extended conformation, perpendicular to the membrane plane. The binding site highlights an integral role for the extracellular loops, together with the helical core, in ligand recognition by this class of GPCRs and suggests a role for ZM241385 in restricting the movement of a tryptophan residue important in the activation mechanism of the class A receptors.
authors.affiliation: Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037 USA.
authors.forename: Veli-Pekka
authors.initials: VP
authors.lastname: Jaakola
authors.forename: Mark T
authors.initials: MT
authors.lastname: Griffith
authors.forename: Michael A
authors.initials: MA
authors.lastname: Hanson
authors.forename: Vadim
authors.initials: V
authors.lastname: Cherezov
authors.forename: Ellen Y T
authors.initials: EY
authors.lastname: Chien
authors.forename: J Robert
authors.initials: JR
authors.lastname: Lane
authors.forename: Adriaan P
authors.initials: AP
authors.lastname: Ijzerman
authors.forename: Raymond C
authors.initials: RC
authors.lastname: Stevens
mesh_terms: D058917:Adenosine A2 Receptor Antagonists; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D008024:Ligands; D011485:Protein Binding; D011487:Protein Conformation; D043705:Receptor, Adenosine A2A / Q000737:chemistry*; D013329:Structure-Activity Relationship; D014227:Triazines / Q000737:chemistry; D014230:Triazoles / Q000737:chemistry; D014364:Tryptophan / Q000737:chemistry; D014422:Turkeys
chemical_list: D058917:Adenosine A2 Receptor Antagonists; D008024:Ligands; D043705:Receptor, Adenosine A2A; D014227:Triazines; D014230:Triazoles; C097270:ZM 241385; D014364:Tryptophan