Table 1.
Binding and signaling properties of WT and mutant hMC3Rs with NDP-MSH as the ligand.
| hMC3R | n | NDP-MSH binding | NDP-MSH-stimulated cAMP | |
|---|---|---|---|---|
| IC50 (nM) | EC50 (nM) | Rmax (% WT) | ||
| WT | 8 | 2.06±0.37 | 0.36±0.02 | 100.00 |
| S69C | 3 | 0.81±0.04b | 0.39±0.07 | 54.67±8.49a |
| A70T | 3 | 1.88±0.56 | 0.37±0.13 | 103.96±2.18 |
| I87T | 3 | 1.08±0.11a | 0.29±0.09 | 91.05±10.14 |
| M134I | 3 | 1.94±0.49 | 0.51±0.08 | 80.31±12.26 |
| L249V | 3 | 1.98±0.41 | 0.43±0.12 | 84.98±18.29 |
| A260V | 3 | 1.53±0.03 | 0.52±0.17 | 91.96±18.09 |
| M275T | 3 | 2.22±0.65 | 0.46±0.04 | 89.72±7.27 |
| T280S | 3 | 1.07±0.13a | 0.29±0.15 | 12.86±5.64b |
| L297V | 3 | 2.30±0.66 | 0.49±0.23 | 106.87±14.46 |
a
Significantly different from the WT hMC3R, p < 0.05.
b
Significantly different from the WT hMC3R, p < 0.01.
The data are expressed as the mean ± SEM for the mutant hMC3Rs. The maximal responses (Rmax) were 2142 ± 507.5 pmol cAMP/106 cells for WT hMC3R.