Table 3. Intracellular calcium release induced by stimulation of mutant hP2Y11–GFP receptors and expression levels of mutant receptors.
Results represent mean EC50 values (μM)±S.E.M., obtained from n (numbers in parentheses) concentration–response curves of 1321N1 cells stably expressing the wild-type (wt) or mutated receptor. The receptor expression level was derived from n experiments.
| EC50 value (μM) | ||||
|---|---|---|---|---|
| hP2Y11-R construct | Residue | ATP | ATP[S] | Receptor expression level (%) (n) |
| wt | 2.37±0.88 (4) | 1.04±0.38 (4) | 100 | |
| R106A | 3.29 | * | n.d. | 76.1±4.7 (4) |
| F109I | 3.32 | 10.7±2.29 (5) | n.d. | 102±13 (7) |
| E186A | EL2 | 32.8±21.1 (5) | 4.92±1.07 (4) | 111±10 (9) |
| Y261A | 6.48 | * | n.d. | 77.4±3.9 (4) |
| R268A | 6.55 | 1806±354 (3) | 247±178 (8) | 143±23 (3) |
| R268Q | 6.55 | 102±20 (5) | 10.3±2.59 (3) | 95.6±8.0 (7) |
| R307A | 7.39 | * | n.d. | 87.5±5.9 (4) |
| A313N | 7.45 | 4.52±0.99 (7) | n.d. | 97.6±11.9 (4) |
*ATP induced no significant increase in intracellular calcium up to concentrations of 10 mM. n.d., Not determined.