Table 1.
Summary of Mutagenesis Experiments
| Mutant | pH50 | n H | n |
|---|---|---|---|
| WT GLIC | 5.50 ± 0.02 | 1.4 ± 0.1 | 16 |
| H126A | 5.24 ±0.10 | 2.3 ± 0.3 | 3 |
| H126E | 5.38 ± 0.07 | 2.2 ± 0.2 | 3 |
| H126K | 5.34 ± 0.06 | 2.0 ± 0.2 | 3 |
| H126L | NR | 3 | |
| H126R | 5.40 ± 0.14 | 2.0 ± 0.4 | 3 |
| H126S | 5.52 ± 0.05 | 2.0 ± 0.2 | 3 |
| H126Y | 5.35 ± 0.04 | 2.6 ± 0.3 | 3 |
| F259TAG + Phe | 5.54 ± 0.07 | 1.1 ± 0.1 | 14 |
| F259TAG + phenyllactic acid | 4.47 ± 0.07 | 2.4 ± 0.3 | 10 |
| A256TAG + Ala | 5.43 ± 0.03 | 1.6 ± 0.6 | 8 |
| A256TAG + Aah | NR | 8 | |
| H234F | NR | 17 | |
| H234L | NR | 12 | |
| H234TAG + His | 5.37 ± 0.04 | 1.5 ± 0.1 | 23 |
| H234TAG + 2-CH3His | NR | 20 | |
| H126TAG + His | 5.56 ± 0.03 | 1.5 ± 0.1 | 13 |
| H126TAG + 2-CH3His | 5.61 ± 0.02 | 1.6 ± 0.1 | 21 |
| H126TAG + 2-CF3His | 5.72 ±0.01 | 1.6 ± 0.1 | 18 |
| H276TAG + His | 5.41 ± 0.03 | 1.7 ± 0.1 | 12 |
| H276TAG + 2-CH3His | 4.52 ± 0.03 | 2.2 ±0.1 | 15 |
| H276TAG + 2-CF3His | 4.52 ± 0.08 | 2.7 ± 0.4 | 16 |
| I261A | 5.05 ± 0.03 | 1.6 ± 0.1 | 11 |
| I261A/H234TAG + His | 4.96 ± 0.02 | 1.3 ± 0.1 | 15 |
| I261A/H234TAG + 2-CH3His | NR | 19 | |
| I261Ga | ~5.0 | ~0.9 | 25 |
| I261G/H234F | NR | 17 | |
| I261G/H234L | NR | 10 | |
| I261G/H234TAG + Hisa | ≤4.5 | ~0.8 | 9 |
| I261G/H234TAG + 2-CH3Hisa | ≤4.5 | ~0.8 | 14 |
| I261G/H234TAG + 2-CF3His | NR | 23 |
The pH50 and nH data are shown as mean ± SEM. NR, nonresponsive. See also Figure S1.
a
Oocytes did not tolerate saturating proton concentrations; pH50 and nH values given are estimated.