Binding characteristics of the wild type and A4 mutant dopamine D2 receptors
Affinity values for [3H]spiperone (Kd) were determined by saturation analyses. The apparent affinity values for dopamine were determined by inhibition of the binding of[3H]spiperone, followed by nonlinear regression analysis of the competition curves. Two-site fits generated values for binding sites with high affinity (Kihigh) and low affinity (Kilow) for dopamine. Each value represents the mean ± S.E. of three or more independent experiments.
Receptor | [3H]Spiperone Kd | Dopamine | Receptor in High-Affinity State | ||
|---|---|---|---|---|---|
| Kihigh | Kilow | ||||
| pM | nM | % | |||
| D2 wild type | 83 ± 13 | 9.0 ± 2.9 | 4.3 ± 0.5 | 22.1 ± 3.5 | |
| D2-A4 | 86 ± 4 | 11.2 ± 3.2 | 3.6 ± 0.7 | 22.7 ± 3.4 | |