Table 1.

IC₅₀ and K_i values obtained from competition binding assays in HEK-293T cells expressing wild type A_2AR or A_2A^Δ40R. Values reported are the mean of three experiments conducted in triplicates fitted to a monophasic competition model.

	A2AR		A2AΔ40R
	IC50 (nM)	Ki (nM)	IC50 (nM)	Ki (nM)	KiΔCT/ Kiwt	ΔΔGa (kcal/mol)
adenosine	1658	183	4804	531	2.9	0.6
NECA	1118	124	2190	242	2.0	0.4
CGS-21680	746	82.5	1690	187	2.3	0.5
PSB-0777	1984	219	8680	960	4.4	0.9
LUF-5834	115	13	166.0	18	1.4	0.2
SCH-58261	6.3	0.7	1030	114	162.3	3.0

A2AR		A2AΔ40R
Bmax	KD (nM)	Bmax	KD (nM)
6959	1.677	9214	1.22

^aExperimental binding free energy differences between wild type (A_2AR) and truncated (A_2A^Δ40R) receptors, calculated as ΔΔG = -RT ln (K_i^ΔCT/K_i^wt) where R is 1.987 cal mol⁻¹ K⁻¹ and T is the temperature of 298°K (-RT = −0.592 kcal mol⁻¹)