Figure 2.

Calcium traces for ATP-α-S (Rp/Sp) isomers at the wild-type and mutant P2Y₁₁GFP receptors stably expressed in 1321N1 cells. Cells pre-incubated with 2 μM fura-2-AM were stimulated with ATP-α-S (Rp/Sp) isomers, and the change in fluorescence (ΔF_340 nm/F_380 nm) was detected. The curves show data from representative experiments using 10 μM ATP-α-S (Rp/Sp) at the receptor mutants and a 10-fold lower concentration at the wild-type receptor. (a) Wild-type receptor, (b) E186A mutant, (c) R268A mutant, (d) R268Q mutant and (e) E186A, R268Q double mutant.