Table 2.

Effect of mutating residues in transmembrane segments on kNBC1 function

Plasmid	pHi minimum	Total buffer capacity (mm pH−1)	Na+-dependent base flux (mm min−1)	Na+-dependent base flux (% of wt)
Y433F	6.58 ± 0.05	34.2 ± 1.69	12.1 ± 1.73*	54.0 ± 7.70*
433Y797Y-433F797F	6.60 ± 0.04	34.0 ± 0.68	12.7 ± 1.03*	56.4 ± 4.58*
D528N	6.64 ± 0.03	36.0 ± 1.67	20.0 ± 2.50	89.0 ± 11.1
D528R	6.56 ± 0.02	38.9 ± 1.50	25.6 ± 1.49	114.3 ± 6.63
F656M	6.64 ± 0.03	37.0 ± 2.72	5.27 ± 0.33*	23.4 ± 1.46*
S684G	6.63 ± 0.02	34.9 ± 1.56	2.20 ± 0.18*	9.79 ± 0.80*
D685N	6.71 ± 0.02	37.5 ± 2.06	5.24 ± 0.32*	23.3 ± 1.44*
D685R	6.58 ± 0.02	34.4 ± 0.74	6.45 ± 0.43*	28.7 ± 1.93*
K854E	6.61 ± 0.02	34.7 ± 1.65	3.15 ± 0.16*	14.0 ± 1.21*
H907D	6.71 ± 0.02	37.2 ± 1.70	8.97 ± 0.79*	39.9 ± 3.50*

^*P < 0.05 versus wt-kNBC1.