TABLE 2.

Summary of microscopic binding/unbinding rates and affinities for the competitive antagonist SR-95531 and binding rates and macroscopic affinities for the agonists GABA and THIP

Data are mean ± S.E.M.

	KD-SR	koff-SR	kon-SR	EC50-GABA	kon-GABA	kon-THIP
	nM	s−1	M−1·s−1	mM	M−1·s−1
α1β2	124	10 ± 1	(8.2 ± 0.7) × 107	6	(2.2 ± 0.4) × 107	(5.5 ± 0.7) × 106
α1β2-GKER	69	7 ± 1	(9.7 ± 0.8) × 107	8	(2.0 ± 0.2) × 107	N.A.
α1β2R207A	230	23 ± 2*	(9.9 ± 1.0) × 107	139	(3.8 ± 0.4) × 106*	(1.9 ± 0.7) × 105*
α1R67Aβ2-GKER	26	12 ± 2	(4.5 ± 0.6) × 108*	1100	(1.4 ± 0.1) × 106*	(5.6 ± 1.7) × 105*
α1R132Aβ2-GKER	542	63 ± 9*	(1.2 ± 0.2) × 108	31	(1.7 ± 0.4) × 107	N.A.

N.A., not available.

^* Differences between mutants and their appropriate control (see Results) were calculated using one-way ANOVA with post-hoc Tukey test at p < 0.05 (Prism 4). GABA unbinding rates were also estimated using a kinetic model (see Fig. 7).