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. Author manuscript; available in PMC: 2015 Feb 1.
Published in final edited form as: Int J Obes (Lond). 2013 Nov 26;38(8):1068–1074. doi: 10.1038/ijo.2013.221

Table 1.

The Ligand Binding and Signaling Properties of Common and Variant MC4Rs in Response to NDP-MSH or α-MSH Stimulation

MC4R Genotype Bmax (%C)a NDP-MSH Binding NDP-MSH-stimulated cAMP α-MSH Binding α-MSH-stimulated cAMP
IC50 (nM) EC50 (nM) Rmax (%C)b IC50 (nM) EC50 (nM) Rmax (%C)c
Common 100 33.93 ± 4.19 1.60 ± 0.27 100 606.28 ± 139.34 10.81 ± 5.04 100
G55V 55.40 ± 9.63e 47.63 ± 16.26 5.41 ± 1.17d 97.08 ± 6.46 N/D 612.34 ± 210.05d 84.87 ± 4.82d
R165G 37.18 ± 3.07f 3.24 ± 0.40e 1.34 ± 0.22 135.46 ± 13.02 271.20 ± 65.53 5.18 ± 1.32 112.50 ± 4.51
R165Q 34.75 ± 4.44f 2.78 ± 0.35e 0.91 ± 0.08d 142.68 ± 6.64d 365.83 ± 86.87 4.46 ± 0.50 134.40 ± 5.28d
C172R N/D N/D 9.60 ± 2.22d 32.86 ± 6.69e N/D 1627.96 ± 430.15e 39.21 ± 7.91e
F202L 99.24 ± 9.32 26.74 ± 5.92 2.15 ± 0.50 125.99 ± 8.55 492.63 ± 83.57 2.79 ± 0.58 92.67 ± 12.58
M208V 74.16 ± 6.18e 70.38 ± 15.20 17.77 ± 5.14d 113.88 ± 13.65 913.47 ± 224.19 270.75 ± 122.34d 139.40 ± 22.24
I269N 42.86 ± 3.08f 10.73 ± 1.39d 0.63 ± 0.23 131.12 ± 9.65 561.20 ± 42.92 40.42 ± 23.73 121.30 ± 6.83d
A303P 22.42 ± 4.55f 2.29 ± 0.34e 0.57 ± 0.13e 98.49 ± 9.23 54.98 ± 14.23d 1.00 ± 0.06 108.30 ± 2.97

Abbreviations: MC4R, melanocortin-4 receptor; NDP-MSH, 4-Norleucine, 7-D-phenylalanine-alpha-melanocyte-stimulating hormone (ultra-potent MC4R agonist); α-MSH, alpha-melanocyte-stimulating hormone; Bmax, maximal binding of 125I-NDP-MSH to cells transiently transfected with common or variant MC4R; %C, percentage of value for common sequence of MC4R; IC50, half-maximal inhibitory concentration; EC50, half-maximal effective concentration; cAMP, 3′-5′-cyclic adenosine monophosphate; Rmax, maximal response; N/D, could not be detected or calculated; SEM, standard error of the mean.

a

Bmax are mean ± SEM of at least six independent experiments, and other parameters are mean ± SEM of at least three independent experiments. Independent samples t tests compared variant MC4Rs with common MC4R.

b

Rmax of common MC4R was 3544.33 ± 471.12 pmol/106 cells with NDP-MSH stimulation.

c

Rmax of common MC4R was 3117.01 ± 472.62 pmol/106 cells with α-MSH stimulation.

d

Significantly different from common MC4R, P <0.05.

e

Significantly different from common MC4R, P <0.01.

f

Significantly different from common MC4R, P <0.001.