Table 3

Mutational analysis of the human A2A AR with respect to ligand binding

Mutation3-aHelix/Position3-bEffect on Ligand Binding and Signal TransductionReference
E13Q1.39Slight reduction of agonist, but not antagonist, affinity IJzerman et al., 1996
T88A/S/R3.36Substantial decrease in agonist, but not antagonist, affinity Jiang et al., 1996
Q89A3.37Slight increase in agonist and antagonist affinity Jiang et al., 1996
Q89N/S/LMarginal changes in ligand binding
Q89H/RAntagonist binding affected
S90A3.38Marginal changes in ligand binding Jiang et al., 1996
S91A3.39Marginal changes in ligand binding Jiang et al., 1996
E151A/Q/DLoss of agonist and antagonist radioligand binding Jiang et al., 1996
E169A∼1000-fold decrease in agonist potency Kim et al., 1996
E169AGain inN 6-substituted agonist affinity Kim et al., 1996
D170KNo change in (radio)ligand binding Kim et al., 1996
P173R
F180A5.41Minor changes in ligand binding Kim et al., 1995
N181S5.42Modest reduction of agonist binding Kim et al., 1995
F182A5.43Loss of agonist and antagonist radioligand binding Kim et al., 1995
F182YModest reduction of agonist binding Kim et al., 1995
F182WModest reduction of agonist binding Kim et al., 1995
H250A6.52Loss of agonist and antagonist radioligand binding; no agonist activity in functional assays Kim et al., 1995
H250F/YModest reduction of agonist binding; no effect on antagonist binding Kim et al., 1995
N253A6.55Loss of agonist and antagonist radioligand binding Kim et al., 1995
C254A6.56Minor changes in ligand binding Kim et al., 1995
F257A6.59Loss of agonist and antagonist radioligand binding Kim et al., 1995
C262G6.64No change in radioligand binding Kim et al., 1996
I274A7.39Loss of agonist and antagonist radioligand binding; ∼30-fold decrease in agonist potency Kim et al., 1995
S277A7.42Substantial decrease in agonist affinity and potency, but antagonist radioligand binding not altered Kim et al., 1995
S277T/C/NMarginal changes in ligand binding Jiang et al., 1996
H278A7.43Loss of agonist and antagonist radioligand binding; ∼300-fold decrease in agonist potency Kim et al., 1995
H278YModest reduction of agonist binding; no effect on antagonist binding Gao et al., 2000
S281A7.46Loss of agonist and antagonist radioligand binding; no agonist activity in functional assays Kim et al., 1995
S281TEnhanced affinity for most agonists Kim et al., 1995
S281NMarginal changes in ligand binding Gao et al., 2000

  • ↵3-a  Amino acids are represented in single-letter code with position number shown. The first amino acid is that of the wild-type receptor, with the second and further residues those used for substitution.

  • ↵3-b  Position on helix, using notation of van Rhee and Jacobson (1996).