Table 3.
Comparison of transport characteristics in NHE3 wild type and mutations
| Point mutation | Amino acid alteration | Basal activity |
Total NHE3 expression (%WT) | % Surface NHE3 expression | Basal activity/surface NHE3 expression (%WT) | ||||
|---|---|---|---|---|---|---|---|---|---|
| Vmax (µm/s) | Vmax (%WT) | K′ (H+)i (µm) | K′(H+)i (%WT) | ||||||
| WT | – | – | 474.9 ± 40.7 | 100 | 0.43 ± 0.05 | 100 | 100 | 11.6 ± 1.8 | 100 |
| Patients 1 and 9 | c.1145G>A | p.Arg382Gln | 123.6 ± 47.4 | 26.5 ± 10.2 | 0.76 ± 0.18 | 192.7 ± 71.9 | 135.8 ± 29.3 | 8.9 ± 1.1 | 25.4 |
| Patient 2 | c.932C>T | p.Ala311Val | 13.8 ± 1.9 | 3.0 ± 0.6 | 0.84 ± 0.10 | 208.7 ± 53.7 | 297.7 ± 56.6 | 3.2 ± 0.6 | 3.7 |
| Patient 3 | c.379G>pA | p.Ala127Thr | 393.8 ± 78.9 | 81.5 ± 9.4 | 0.5 ± 0.06 | 115.2 ± 4.1 | 117.3 ± 17.5 | 12.1 ± 1.7 | 66.6 |
| Patients 4 and 5 | c.805G>A | p.Ala269Thr | 131.1 ± 18.3 | 28.5 ± 5.6 | 0.77 ± 0.11 | 177.3 ± 6.3 | 108.3 ± 18.1 | 3.2 ± 0.8 | 95.4 |