Inhibition of cAMP accumulation by wild-type and mutant D2Lreceptors
| Drug | D2 | N52Q | S121A | S121N | |
|---|---|---|---|---|---|
| Dopamine | EC50(nM) | 27 (17–42) | 21 (14–32) | 55 (31–99) | 198 (114–340)4-a |
| Max (%) | 64 ± 10 | 78 ± 4 | 49 ± 8 | 54 ± 7 | |
| Quinpirole | EC50(nM) | 10 (8–14) | 36 (20–67) | 19 (18–20) | 105 (97–114)4-a |
| Max (%) | 63 ± 12 | 69 ± 7 | 59 ± 5 | 57 ± 1 | |
| 7-OH-DPAT | EC50(nM) | 41 (20–84) | 20 (15–27) | 30 (16–53) | 102 (98–107) |
| Max (%) | 57 ± 8 | 74 ± 3 | 58 ± 12 | 64 ± 5 |
HEK293 cells stably expressing the indicated wild-type or mutant D2L receptor were incubated with 30 μM forskolin and increasing concentrations of the indicated drugs, and cAMP formation was determined as described under Experimental Procedures. EC50 values, expressed in nanomolar, were calculated from the dose-response curves and are the geometric means of three to five independent experiments, followed in parentheses by the limits defined by the asymmetrical S.E. The mean ± S.E. is shown for maximal inhibition of forskolin-stimulated activity (Max), expressed as a percentage of total cAMP accumulation.
↵4-a P < 0.05 compared with the potency of D2L for that drug.