The effects of protein phosphorylation on 6,7-ADTN-stimulated D2 receptor signaling.
| EC50(nM) | Maximum Inhibition (%) | |
|---|---|---|
| A7-D2 | 0.25 ± 0.10 (4) | 79.50 ± 4.29 (4) |
| A7-D2 + PMA | 0.83 ± 0.13 (3)4-150 | 81.18 ± 0.96 (3) |
| A7-D2S358D | 0.75 ± 0.15 (4)4-150 | 64.84 ± 2.73 (4)4-150 |
| A7-D2S358D + PMA | 1.24 ± 0.37 (3) | 72.60 ± 2.44 (3) |
| M2-D2 | 3.95 ± 0.67 (4) | 34.30 ± 4.71 (4) |
| M2-D2 + PMA | 4.03 ± 0.98 (3) | 40.32 ± 5.20 (3) |
| M2-D2S358D | 6.13 ± 0.95 (3) | 39.40 ± 3.57 (3) |
D2 and D2S358D receptors were stably expressed in M2 and A7 cells. The EC50 values (nM) and the maximum inhibition (%) were calculated from the dose-response curves of cAMP production. In PMA experiments, cells were incubated with forskolin (10 μM) and increasing concentrations of 6,7-ADTN in the presence of 100 nM PMA (10 min preincubation). PMA treatment alone did not change basal and forskolin-stimulated cAMP production. Stable clones with similar receptor expression levels were tested. The expression levels were 1.48 pmol/mg of protein (A7-D2) versus 1.6 pmol/mg of protein (A7-D2S358D) and 1.45 pmol/mg of protein (M2-D2) versus 1.3 pmol/mg of protein (M2-D2S358D). Data shown are the mean ± S.E. from three to four experiments, indicated in parentheses.
↵4-150 P<.05, compared with A7-D2 cells, unpaired Student"s t test.