TABLE I.
Voltage Activation Relations for Shaker Kv Channels with Mutations at P475
| Residue | V50 | z | n |
|---|---|---|---|
| mV | |||
| P (Wt) | −30.5 ± 0.6 | 3.8 ± 0.1 | 37 |
| G | 44.6 ± 1.3 | 2.2 ± 0.02 | 4 |
| S | 195.0 ± 5.7 | 1.2 ± 0.03 | 4 |
| T | −15.0 ± 1.5 | 3.3 ± 0.08 | 8 |
| Y | −48.3 ± 0.5 | 3.7 ± 0.1 | 10 |
| V | 64.8 ± 1.0 | 1.6 ± 0.08 | 6 |
| I | 63.9 ± 1.7 | 1.2 ± 0.04 | 5 |
| M | −11.9 ± 0.2 | 2.8 ± 0.06 | 9 |
| C | 146 ± 3.0 | 1.3 ± 0.07 | 3 |
| F | −21.6 ± 0.8 | 3.0 ± 0.09 | 10 |
| W | −49.4 ± 1.8 | 4.0 ± 0.3 | 14 |
| Q | −95.2 ± 1.0 | 2.6 ± 0.08 | 24 |
| N | −83.6 ± 0.9 | 3.2 ± 0.1 | 8 |
| K | −94.2 ± 3.6 | 2.6 ± 0.5 | 5 |
| H | −76.0 ± 6.3 | 3.1 ± 0.2 | 5 |
| R | −72.8 ± 2.8 | 3.0 ± 0.2 | 4 |
| E | −96.1 ± 3.2 | 3.1 ± 0.23 | 4 |
| D | −98.5 ± 2.3 | 3.3 ± 0.4 | 10 |
Tail current voltage-activation relations were obtained for most mutants using 50 mM Rb+ as the external charge carrier and fit with single Boltzmann functions. P475D was obtained using 50 mM K+ as the external charge carrier. P475L results in undetectable ionic or gating currents and P475A results in gating currents but no ionic currents (i.e., a nonconducting mutant). n corresponds to the number of experiments.