Table 1. Summary of calculated values of apparent pH_50A of activation, pH_50SSD steady-state desensitization and corresponding Hill coefficients: n Overlap of activation and desensitization currents in mutants with decreased desensitization prevented to determine pH_50SSD values, they are reported as <pH 6.0 or ND.

Numbers are the mean ± SD of five to eight independent measurements.

	pH50a	N		pH50ssd	N
WT	6.69 ± 0.21	3.5		7.09 ± 0.05	10
Q278G	6.68 ± 0.18	3.4		7.07 ± 0.02	14
Q276 Mutants
	pH50a	n		pH50ssd	n
Q276G	6.67 ± 0.15	3.5		<6.00	ND
Q276A	6.71 ± 0.12	4.2		<6.00	ND
Q276D	6.68 ± 0.31	4.7		<6.00	ND
Q276C	6.61 ± 0.21	3.9		<6.60	ND
Q276E	6.66 ± 0.18	4.2		6.80 ± 0.11	8
Q276N	6.64 ± 0.23	3.4		<6.60	ND
Q276L	6.71 ± 0.13	3.8		6.6 ± 0.20	3
Q276K	6.55 ± 0.32	3.7		<6.60	ND
Q276R	6.62 ± 0.23	4.1		<6.30	ND
Q276Y	6.75 ± 0.11	3.8		<6.20	ND
Q276W	6.72 ± 0.09	3.4		<6.00	ND
L415 Mutants
	pH50a	n		pH50ssd	n
L415G	4.88 ± 0.11	1.3		<6.00	ND
L415A	4.50 ± 0.20	2		<6.00	ND
L415D	5.00 ± 0.11	1		<6.00	ND
L415C	6.00 ± 0.10	2.1		7.02 ± 0.05	18
L415V	6.70 ± 0.11	6		7.02 ± 0.07	15
L415E	6.60 ± 0.10	3.1		6.90 ± 0.05	8.9
L415T	6.68 ± 0.18	2.3		6.95 ± 0.04	15
L415Q	6.61 ± 0.11	2.6		6.82 ± 0.03	4.8
L415M	6.70 ± 0.14	6.3		<6.00	ND
L415R	6.46 ± 0.21	2.3		<6.00	ND
L415F	4.41 ± 0.12	3.7		<6.00	ND
L415Y	4.69 ± 0.22	1.5		<6.00	ND
N416 Mutants
	pH50a	n		pH50ssd	n
N416G	6.50 ± 0.02	3.6		7.04 ± 0.03	7
N416A	6.50 ± 0.06	8		6.80 ± 0.01	6
N416C	6.68 ± 0.05	5.3		7.03 ± 0.05	5.6
N416S	6.58 ± 0.04	3.5		7.08 ± 0.01	7
N416Q	6.79 ± 0.02	7.8		6.71 ± 0.06	5.6
N416L	6.85 ± 0.03	5.2		6.96 ± 0.01	4
N416K	6.60 ± 0.05	8		>6.00	ND
N416R	6.22 ± 0.04	5		>6.00	ND
N416Y	4.85 ± 0.03	1.8		>6.00	ND