Table 1.
Binding and signaling properties of the 8 new mutant hMC3Rs with NDP-MSH as the ligand.
| hMC3R | NDP-MSH binding | Basal signaling (% WT) | NDP-MSH-stimulated cAMP | ||
|---|---|---|---|---|---|
| IC50 (nM) | RO (% WT) | EC50 (nM) | Rmax (% WT) | ||
| WT | 6.45 ± 0.87 | 100 ± 0 | 100 ± 0 | 1.28 ± 0.49 | 100 ± 0 |
| S17T | 5.73 ± 0.48 | 136.00 ± 15.43 | 107.50 ± 24.68 | 1.24 ± 0.68 | 81.87 ± 17.35 |
| F82S | ND | 8.07 ± 1.45c | 84.05 ± 19.86 | ND | 22.99 ± 2.26c |
| D158Y | ND | ND | 54.05 ± 8.81b | ND | ND |
| V177I | 4.33 ± 1.61 | 82.96 ± 11.96 | 88.01 ± 21.52 | 0.62 ± 0.14 | 61.81 ± 10.02 |
| L249F | 7.74 ± 1.99 | 128.39 ± 23.49 | 69.48 ± 20.70 | 4.98 ± 2.54 | 50.02 ± 2.74b |
| R257S | 5.88 ± 0.12 | 73.38 ± 8.36a | 78.80 ± 13.97 | 3.26 ± 1.62 | 44.05 ± 12.03a |
| L285V | 6.07 ± 1.02 | 93.68 ± 13.78 | 52.40 ± 11.86b | 5.76 ± 2.64 | 29.71 ± 3.22b |
| L299V | ND | 8.65 ± 1.51c | 78.55 ± 15.31 | 14.84 ± 4.29a | 38.53 ± 5.31b |
a Significantly different from the WT hMC3R, P < 0.05.
b Significantly different from the WT hMC3R, P < 0.01.
c Significantly different from the WT hMC3R, P < 0.001.
ND, not detected.
The data are expressed as the mean ± SEM of at least three independent experiments for IC50, EC50, and Rmax, and at least six independent experiments for RO and basal signaling. The basal cAMP was 36.88 ± 5.89 pmol/106 cells and the Rmax was 2526.00 ± 502.11 pmol cAMP/106 cells for the WT hMC3R.