Analysis of Gp-V relations from wild-type and PxAx mutant Kv channels
Chord peak conductance-voltage relations were analyzed as described under Materials and Methods. Assuming Boltzmann distributions, the midpoint voltage V½ and the slope factor k are the best-fit parameters that described these relations. The apparent gating charge Z was calculated as RT/kF, R is the gas constant, T is the absolute temperature, and F is the Faraday constant. ΔV½ = V½,mut - V½,wt. The wild-type and mutant tandem heterodimer subunits are as explained in Fig. 6. The ΔV½ values of the tandem heterodimer dimer PVAV mutants are relative to the V½ of the tandem heterodimer composed of wild-type subunits.
Kv channel | V½ | Z | ΔV½ | n |
|---|---|---|---|---|
| mV | e 0 | mV | ||
| Kv1.4 | −17.7 ± 2.4 | 0.87 ± 0.004 | - | 4 |
| Kv1.4-P557A | +80 | 1.12 ± 0.05 | +98 | 5 |
| Kv2.1 | +2.6 ± 3.8 | 1.62 ± 0.11 | - | 5 |
| Kv2.1-P410A | +16.6 ± 3.4 | 1.47 ± 0.07 | +14 | 4 |
| Kv3.4 | +7.1 ± 2.8 | 2.39 ± 0.04 | 3 | |
| Kv3.4-P469A | +82.6 ± 17.6 | 1.17 ± 0.19 | +76 | 3 |
| Δ28-Kv3.4 | −5.2 ± 1.5 | 2.77 ± 0.15 | - | 4 |
| Δ28-Kv3.4-P469A | +61.5 ± 11.1 | 0.78 ± 4.8 | +67 | 6 |
| Kv4.3 | −6.5 ± 4.0 | 0.98 ± 0.02 | - | 5 |
| Kv4.3-P400A | +22.4 ± 2.0 | 0.71 ± 0.01 | +29 | 4 |
| Kv3.4-Shaw2 Tandem | +12.2 ± 2.3 | 1.6 ± 0.06 | - | 4 |
| Kv3.4-Shaw2[P410A] | +28.7 ± 3.6 | 1.26 ± 0.07 | +16.5 | 3 |
| Kv3.4[P469A]-Shaw2 | +49 ± 2.2 | 0.88 ± 0.02 | +36.8 | 3 |
| Kv3.4[P469A]-Shaw2[P410A] | +76 ± 12 | 0.41 ± 0.04 | +63.8 | 5 |