Table 3.

Modulation by intracellular chloride of inward currents in mutant α1, α1β GlyR, and α1β2γ2 GABA receptors

Receptor type	α1, GlyR Intracellular Cl			Gly α1β, α1 mutants Intracellular Cl			Gly α1β, β mutants Intracellular Cl			α1β2γ2, α1 mutants Intracellular Cl			α1β2γ2, β2 mutants Intracellular Cl			α1β2γ2, γ2 mutants Intracellular Cl
	10 mm	130 mm	p	10 mm	130 mm	p	10 mm	130 mm	p	10mm	130 mm	p	10 mm	130 mm	p	10 mm	130 mm	p
19′	0.42 ± 0.05 (11)	0.48 ± 0.05 (7)	0.43	0.97 ± 0.09 (7)	0.96 ± 0.13 (8)	0.95	N/A	N/A	N/A	4.6 ± 0.6 (9)	5.2 ± 0.4 (9)	0.44	7.8 ± 0.9 (5)	20.1 ± 2.7 (6)	<0.0001	7.9 ± 1.1 (7)	18.8 ± 2.5 (10)	0.0039
24′	1.08 ± 0.12 (5)	1.54 ± 0.17 (12)	0.12	0.61 ± 0.07 (7)	1.05 ± 0.17 (5)	0.023	4.3 ± 0.5 (8)	12.8 ± 1.3 (6)	0.0002	6.8 ± 0.5 (10)	11.3 ± 1.8 (9)	0.02	6.1 ± 0.9 (8)	14.2 ± 1.4 (13)	0.0005	14.7 ± 2.4 (7)	35.8 ± 5.2 (6)	<0.001
29′	15.5 ± 0.9 (12)	16.8 ± 1.3 (11)	0.43	55.4 ± 4.3 (6)	67.6 ± 4.0 (8)	0.063	6.4 ± 0.7 (5)	10.9 ± 1.2 (7)	0.0171	9.7 ± 0.8 (10)	17.8 ± 1.2 (11)	<0.0001	N/A	N/A	N/A	26.9 ± 3.8 (7)	51.2 ± 2.4 (7)	<0.0002
α1Δ GLIC	13.2 ± 1.2 (12)	44.7 ± 4.4 (13)	<0.0001
A−1′E	44.0 ± 1.7 (8)	46.4 ± 2.3 (10)	0.45

The columns give the weighted time constants of decay for currents elicited in outside-out patches by the application of 1 ms pulses of saturating concentrations of glycine or GABA (3 mm; see Materials and Methods). Values are averages ± SEM, expressed in milliseconds. Number of patches in parentheses. p values from unpaired, two-tailed t test. The effect of intracellular chloride concentrations on the time course of the current relaxation was tested by using pipette solutions containing either 10 or 130 mm chloride on different patches. The current relaxation was measured for inward current only (−100 mV). Residues at positions 19′, 24′, and 29′ were neutralized to Ala or Cys depending on the expression level attainable. Mutants highlighted in bold abolish or decrease drastically the effect of the chloride modulation on the time course of the current relaxation.