Fig. 2. Displacement of binding of the antagonist radioligand [3H]XAC from Tag3-A2a wild type (●) and S277A (○) mutant receptors expressed in COS-7 cells.
Competitors used were CGS 21680 (A), 2-chloroadenosine (B), and N6-phenylisopropyladenosine (C). Competition binding studies were carried out using membrane homogenates prepared from transfected COS-7 cells, as described under “Experimental Procedures.” Data are presented as means ± S.E. of two or three independent experiments, each performed in duplicate.