TABLE 2

The effect of mutations on OX1 mediation of orexin-A-induced [Ca2+]i response

EC50, Hill slope (nH), and relative efficacy (Emax) values for the orexin-A-induced [Ca2+]i response in the HEK293 cells transiently transfected with the WT and mutated hOX1 receptors. The data is mean ± S.E. of eight concentration-response measurements (each performed in duplicate) from four independent transfections. The mutations that affected the potency and relative efficacy of orexin-A compared with WT are shown in boldface type.

hOX17TM PositionOrexin-A
EC50EC50 (mut)/EC50 (WT)nHRelative Emax
nM
WT0.9 ± 0.20.7 ± 0.1100
Q126A3.322.2 ± 0.22.40.7 ± 0.159.1 ± 10.1
A127T3.331.6 ± 0.41.80.8 ± 0.097.9 ± 32.9
V130A3.3627.5 ± 2.530.60.7 ± 0.198.9 ± 31.4
D203A45.51367.4 ± 75.0408.20.8 ± 0.1155.2 ± 53.1
W206A45.54376.0 ± 102.0417.80.8 ± 0.245.0 ± 8.0
Y215A5.38367.0 ± 95.0407.80.6 ± 0.165.0 ± 9.0
F219A5.42125.6 ± 26.5139.60.8 ± 0.190.1 ± 48.6
Y224A5.4776.0 ± 41.384.40.6 ± 0.183.7 ± 40.6
Y311A6.48147.5 ± 67.1163.90.9 ± 0.153.4 ± 12.9
H344A7.39217.0 ± 63.9241.10.9 ± 0.164.5 ± 7.3
Y348A7.437.8 ± 3.08.70.8 ± 0.062.4 ± 18.9