Table 1

Summary of ligand binding results

GnRH analogKiFold change
Wild-TypeMutant
nM
GnRH1-a 6.79  ± 1.08212  ± 40.61-160 31.2
[Gln8]-GnRH923  ± 2221240  ± 2271.35
[Glu8]-GnRH>10 000>10 000—
[His5,d-Tyr6]-GnRH0.48  ± 0.121-b 1.36  ± 0.201-150 1-b 2.83
[d-Ala6,N-Me-Leu7,Pro9-NHEt]-GnRH0.97  ± 0.351.55  ± 0.091.60
[d-Trp6,Pro9-NHEt]-GnRH0.15  ± 0.040.27  ± 0.061.80
[d-Trp6,Gln8,Pro9-NHEt]-GnRH1.86  ± 0.191.67  ± 0.430.82
[6,7 γ-lactam]-GnRH1.37  ± 0.074.66  ± 0.361-160 3.40
GnRH II ([His5,Trp7,Tyr8]-GnRH)193.7  ± 28.5213.3  ± 72.41.10
Antagonist 129-620.86  ± 0.211.52  ± 0.281.76
Antagonist 260.80  ± 0.131.13  ± 0.191.41

Competition binding assays were performed on COS-1 cells transiently transfected with wild type or mutant GnRH receptors, using125I-[His5, d-Tyr6]-GnRH and various concentrations of unlabeled ligands as described underMaterials and Methods. K i values are presented as mean ± S.E. Statistical analyses were performed using pK i values as described under Materials and Methods. The fold change was calculated as the ratio of theK i values of the mutant and wild-type receptors.

    • ↵1-150 , Significantly different from wild type,p < 0.05.

    • ↵1-160 , Significantly different from wild type, p< 0.001.

    • ↵1-a  GnRH sequence: pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2.

    • ↵1-b  K d values are reported for the homologous ligand, [His5,d-Tyr6]-GnRH.