Table 2.

EC₅₀ value and efficacy of adenine determined in [³⁵S]GTPγS binding studies at membrane preparations of Sf9 cells, coexpressing the rat adenine wild-type or mutant receptors, respectively, and mammalian G proteins (Gα_i2 and Gβ₁γ₂)

	EC50 (nM)	Number	p	Fold shifta	Emax (% ± SEM)	p
wt	605 ± 79	5			136 ± 12
F110A	44 ± 8	3	**	14	129 ± 9	ns
N115A	166 ± 52	4	**	4	124 ± 11	ns
N173A	131 ± 2	3	**	5	146 ± 8	ns
F179A	82 ± 15	3	**	7	141 ± 6	ns
N194A	Very minor effect	5			nd
F195A	107 ± 10	3	**	6	174 ± 12	ns
L201A	No effect	4			nd
H252A	718 ± 132	3	ns	1	146 ± 15	ns
Y268A	7,082 ± 1,220	4	***	0.08	229 ± 20	*

Number, number of experiments performed in triplicates; nd not determined; E_max value, maximal effect of the specific binding of [³⁵S]GTPγS; binding in the absence of adenine was set at 100 %; p, significance was determined using the unpaired t test, mutants were compared to rAdeR coexpressed with G proteins; ns not significant

p > 0.05; *p < 0.05; **p < 0.01; ***p < 0.001

^aThe shift represents the ratio of EC₅₀ (wt)/EC₅₀ (mutant)