Table 2. Fitted parameters for α4β2, α4β2V287L, α5α4β2, and α5α4β2V287L ACh concentration-response relations in HEK cells using a membrane-potential dye.

Receptor	EC50 (μM)a	Hill coefficient	Maximum Responseb	dfc
α4β2	6 ± 1d	0.72 ± 0.06	0.95 ± 0.02	13
α4β2V287L	0.4 ± 0.1#e	0.7 ± 0.1	0.53 ± 0.02***f	13
α5α4β2	26 ± 5#	0.57 ± 0.04	1.06 ± 0.03	13
α5α4β2V287L	0.5 ± 1#	1.0 ± 0.3	0.67 ± 0.03***	13

^aConcentration-response relations were fit to the Hill equation with three free parameters (EC50, Hill coefficient, maximum response).

α4β2V287L

^bMutant and α4β2 WT responses were normalized to the α4β2 WT value at 1 mM ACh. Similarly, α5α4β2V287L mutant and α5α4β2 WT responses were normalized to the α5α4β2 WT value at 1 mM ACh.

^cDegrees of freedom (df) are the number of concentrations in concentration-response relation minus the three free parameters.

^dParameter values are mean ± S.E.

^e(^#) Significantly different from the α4β2 WT value at the 0.05 level.

^f(***) Significantly different from the corresponding WT (α4β2, α5α4β2) value at the 0.001 level.