TABLE 5

Efficacy and potency of melanocortin agonists to stimulate cAMP production of WT and mutant hMC4Rs rescued by DCPMP pretreatment

Data shown are the mean ± S.E.M. of the number of experiments indicated in parentheses. EC50 is the concentration of ligand that results in 50% stimulation of the maximal response (Rmax).

Agonist and MutationLocationEC50Rmax
Untreated10 μM DCPMPUntreated10 μM DCPMP
nMfmol/104 cells
NDP-α-MSH
    WT4.01 ± 0.82 (7)3.9 ± 0.9 (9)170.2 ± 31.7 (7)393.2 ± 40.0 (9)**
    N62STM 1N.A.18.5 ± 0.8 (3)*N.A.275.4 ± 57.1 (3)
    R165WTM 4N.A.4.8 ± 1.3 (3)N.A.297.0 ± 23.4 (3)
    C271YEXL3N.A.175 ± 82.1 (4)**N.A.152.9 ± 50.2 (4)a
α-MSH
    WT300 ± 70 (9)370 ± 60 (9)196.7 ± 45.3 (9)405.2 ± 37.3 (9)*
    N62STM 1N.A.2020 ± 700 (3)**bN.A.367.3 ± 82.5 (3)
    R165WTM 4N.A.1500 ± 400 (5)*bN.A.213.5 ± 64.8 (5)
    C271YEXL3N.A.12,300 ± 6500 (3)***cN.A.106.7 ± 8.4 (3)b
  • N.A., not applicable.

  • a Significantly different from treated WT hMC4R, P < 0.01.

  • b Significantly different from treated WT hMC4R, P < 0.05.

  • c Significantly different from treated WT hMC4R, P < 0.001.

  • * Significantly different from untreated WT hMC4R, P < 0.05.

  • ** Significantly different from untreated WT hMC4R, P < 0.01.

  • *** Significantly different from untreated WT hMC4R, P < 0.001.