Table 2. MT₁ Variant Receptors Bind to Melatonin as well as the MT₁-WT Except P80L^a.

receptors	Kd (pM) ± SEM
Wild Type	101 ± 9.3
V52A	99 ± 6.9
R54W	178 ± 25
P80L	No binding
S87L	136 ± 19
I88V	79 ± 4.5
G96D	81 ± 8.7
I112N	244 ± 75
R125C	227 ± 61
H131R	62 ± 11
L138P	171 ± 61
G166E	63 ± 1.2
I212T	101 ± 5.0
I257F	168 ± 7.2
A266V	224 ± 43
S267G	186 ± 54
R307S	40 ± 2.5
I309T	75 ± 5.6
C314R	48 ± 7.8
K334N	395 ± 68
N342S	140 ± 43
V345I	69 ± 1.8

^aMelatonin dissociation constant measured by 2-(¹²⁵I)Iodomelatonin binding experiment on MT₁ variants with at least one signaling defect. Data represents means ± SEM of at least three experiments.