TABLE 3.

Mutations of the non-conserved residues in TM3 of the hMC4R on ¹²⁵I-NDP-MSH binding and cAMP production

	Receptor expression	NDP-MSH Ki	NDP-MSH EC5O
	%WT	nM
hMC4R-WT	100	3.6 ± 0.1	0.8 ± 0.2
N123A	96 ± 2.2	4.3 ± 0.2	1.6 ± 0.5
N123D	76 ± 12.2	69.3 ± 0.2a	45.6 ± 7.1a
I129A	87 ± 3.5	4.21 ± 0.1	1.3 ± 0.3
C130A	92 ± 7.7	2.9 ± 0.3	1.8 ± 0.7
S131A	90 ± 8.1	4.3 ± 0.5	2.1 ± 0.1
C138A	91 ± 5.5	4.9 ± 0.6	0.8 ± 0.1
S142A	93 ± 3.5	5.6 ± 0.8	1.9 ± 0.9

^ap < 0.05 compared with WT receptor.