Thermostabilised HUMAN A2a Receptor with CGS21680 bound

Experimental Data Snapshot

  • Resolution: 2.60 Å
  • R-Value Free: 0.312 
  • R-Value Work: 0.259 
  • R-Value Observed: 0.261 

Starting Model: experimental
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Molecular Determinants of Cgs21680 Binding to the Human Adenosine A2A Receptor.

Lebon, G.Edwards, P.C.Leslie, A.G.W.Tate, C.G.

(2015) Mol Pharmacol 87: 907

  • DOI: https://doi.org/10.1124/mol.114.097360
  • Primary Citation of Related Structures:  
    4UG2, 4UHR

  • PubMed Abstract: 

    The adenosine A2A receptor (A(2A)R) plays a key role in transmembrane signaling mediated by the endogenous agonist adenosine. Here, we describe the crystal structure of human A2AR thermostabilized in an active-like conformation bound to the selective agonist 2-[p-(2-carboxyethyl)phenylethyl-amino]-5'-N-ethylcarboxamido adenosine (CGS21680) at a resolution of 2.6 Å. Comparison of A(2A)R structures bound to either CGS21680, 5'-N-ethylcarboxamido adenosine (NECA), UK432097 [6-(2,2-diphenylethylamino)-9-[(2R,3R,4S,5S)-5-(ethylcarbamoyl)-3,4-dihydroxy-tetrahydrofuran-2-yl]-N-[2-[[1-(2-pyridyl)-4-piperidyl]carbamoylamino]ethyl]purine-2-carboxamide], or adenosine shows that the adenosine moiety of the ligands binds to the receptor in an identical fashion. However, an extension in CGS21680 compared with adenosine, the (2-carboxyethyl)phenylethylamino group, binds in an extended vestibule formed from transmembrane regions 2 and 7 (TM2 and TM7) and extracellular loops 2 and 3 (EL2 and EL3). The (2-carboxyethyl)phenylethylamino group makes van der Waals contacts with side chains of amino acid residues Glu169(EL2), His264(EL3), Leu267(7.32), and Ile274(7.39), and the amine group forms a hydrogen bond with the side chain of Ser67(2.65). Of these residues, only Ile274(7.39) is absolutely conserved across the human adenosine receptor subfamily. The major difference between the structures of A(2A)R bound to either adenosine or CGS21680 is that the binding pocket narrows at the extracellular surface when CGS21680 is bound, due to an inward tilt of TM2 in that region. This conformation is stabilized by hydrogen bonds formed by the side chain of Ser67(2.65) to CGS21680, either directly or via an ordered water molecule. Mutation of amino acid residues Ser67(2.65), Glu169(EL2), and His264(EL3), and analysis of receptor activation either in the presence or absence of ligands implicates this region in modulating the level of basal activity of A(2A)R.

  • Organizational Affiliation

    Institut de Génomique Fonctionelle, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5203, Institut National de la Sante et de la Recherche Medicale U1191, Université de Montpellier, Montpellier, France (G.L.); and Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, United Kingdom (P.C.E., A.G.W.L., C.G.T.) guillaume.lebon@igf.cnrs.fr cgt@mrc-lmb.cam.ac.uk.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Membrane Entity: Yes 
UniProt & NIH Common Fund Data Resources
Find proteins for P29274 (Homo sapiens)
Explore P29274 
Go to UniProtKB:  P29274
GTEx:  ENSG00000128271 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP29274
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on NGI

Download Ideal Coordinates CCD File 
C23 H29 N7 O6
Binding Affinity Annotations 
IDSourceBinding Affinity
NGI BindingDB:  4UHR Ki: min: 8.8, max: 503 (nM) from 16 assay(s)
Kd: min: 4.3, max: 632 (nM) from 10 assay(s)
IC50: 19 (nM) from 1 assay(s)
EC50: min: 2.1, max: 2.00e+4 (nM) from 4 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 2.60 Å
  • R-Value Free: 0.312 
  • R-Value Work: 0.259 
  • R-Value Observed: 0.261 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 60.407α = 90
b = 59.187β = 92.83
c = 65.058γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-04-08
    Type: Initial release
  • Version 1.1: 2015-05-13
    Changes: Database references
  • Version 1.2: 2019-04-03
    Changes: Data collection, Other, Source and taxonomy
  • Version 1.3: 2024-01-10
    Changes: Data collection, Database references, Derived calculations, Other, Refinement description