TABLE 2.

Second-order rate constants (k₂) for reaction of MTS reagents with mutant receptors in the absence (Control) and presence of GABA, PB, and SR-95531 NFE, no functional effect; MTS reagents react but have no functional effect on subsequent GABA responses. ^*, ^** indicate values significantly different from control, with p < 0.05 and p < 0.001, respectively. Values are the mean ± S.E.

Receptor	Controla		GABAaEC80–90		SR-95531		Pentobarbital		Pentobarbital
	k2 M–1S–1	n	k2 M–1S–1	n	k2 M–1S–1	n	k2 M–1S–1	n	k2 M–1S–1	n
					10 μm		500 μm		50 μm
α1K219Cβ2b	2070 ± 300	4	580 ± 130**	3	700 ± 110**	4	NFE	3	710 ± 190	4
α1K221Cβ2b	2110 ± 290	6	1600 ± 80	4	1570 ± 250	4	970 ± 250*	4	1750 ± 260	3
α1β2K213Cc	1900 ± 340	5	5540 ± 320**	7	1610 ± 200	4	NFE	3	1590 ± 340	3
α1β2K215Cc	1990 ± 220	6	7560 ± 1750**	3	3050 ± 510	3	2590 ± 250	3	2850 ± 440	4

^aReported in Ref. 13

^bMTSEA-biotin reaction rates are reported

^cMTSET⁺ reaction rates are reported