TABLE 1

The effect of mutations on OX2 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 hOX2 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 of orexin-A compared with WT are shown in boldface type.

hOX27TM PositionOrexin-A
EC50EC50 (mut)/EC50 (WT)nHRelative Emax
nM
WT0.6 ± 0.10.5 ± 0.0
T111A2.61151.0 ± 22.2243.50.7 ± 0.0114.4 ± 13.0
Q134A3.3213.8 ± 2.122.31.4 ± 0.162.3 ± 1.1
T135A3.330.5 ± 0.10.80.6 ± 0.1109.3 ± 11.2
V138A3.362.8 ± 0.44.40.7 ± 0.092.1 ± 10.0
S139A3.371.5 ± 0.32.50.6 ± 0.086.1 ± 8.6
D211A45.51258.0 ± 57.2416.10.8 ± 0.1126.4 ± 16.4
W 214A45.5438.7 ± 12.262.40.7 ± 0.171.3 ± 7.4
Y223A5.38114.0 ± 14.1183.91.0 ± 0.161.2 ± 1.2
F227A5.42149.0 ± 34.8240.31.1 ± 0.164.3 ± 6.3
F228A5.431.8 ± 0.73.00.7 ± 0.176.2 ± 2.1
Y232A5.4717.6 ± 3.128.41.2 ± 0.144.9 ± 4.5
Y317A6.4811.0 ± 6.117.71.0 ± 0.149.6 ± 6.7
Y317F6.480.8 ± 0.31.30.6 ± 0.172.3 ± 9.7
I320A6.510.6 ± 0.20.90.6 ± 0.097.0 ± 5.4
F346A7.3533.8 ± 8.854.51.1 ± 0.260.7 ± 13.2
H350A7.3930.7 ± 5.249.51.1 ± 0.263.0 ± 10.7
V353A7.421.2 ± 0.51.90.6 ± 0.184.8 ± 14.7
Y354A7.432.3 ± 0.93.70.7 ± 0.166.1 ± 12.0