Table 2. Bioactivities of inactivating eel LH/CGR mutants and C-terminal deleted mutant

Eel LH/CG receptors	cAMP responses
	Basal1 (nM/104 cells)	Log (EC50) (ng/mL)	Rmax2 (nM/104 cells)
Eel LH/CGR-wt	2.2±1.4	108 (86.7 to 144.5)3	76.4±2.0
Eel LH/CGR-D417N	0.8±0.3	253.9 (2.3-fold) (227 to 288.2)	44.2±0.7
Eel LH/CGR-Y558F	1.6±0.5	345.4 (3.2-fold) (12.4 to 16.7)	38.8±1.1
Eel LH/CGR-t651	0.7±0.02	-	-

Values are the means±SEM of triplicate experiments. The log (EC₅₀) values were determined from the concentration-response curves obtained from the in vitro bioassays.
Basal cAMP level average without agonist treatment.
Rmax average cAMP level/10⁴ cells.
Geometric mean (95% confidence limit) of at least three experiments.
LH, luteinizing hormone; CGR, choriogonadotropin receptor; cAMP, cyclic adenosine monophosphate; EC₅₀, effective concentration.