TABLE I.
Effects of Charge Removal on the Voltage Dependence of Homomeric KCNQ1 Activation
| Channel | V1/2, mV | k, mV | n |
|---|---|---|---|
| wt KCNQ1 | −35.67 ± 0.53 | 9.29 ± 0.43 | 14 |
| K218A | −31.54 ± 0.96 | 10.18 ± 0.46 | 12 |
| R228A | +36.14 ± 2.20 | 24.97 ± 3.4 | 14 |
| R231A | NA | NA | 22 |
| R237A | −17.59 ± 1.42 | 10.33 ± 1.29 | 14 |
| D242A | −62.69 ± 3.38 | 10.40 ± 3.08 | 9 |
| R243A | −19.59 ± 4.97 | 14.78 ± 4.5 | 11 |
| R249A | −29.39 ± 1.23 | 8.89 ± 0.95 | 13 |
| R259A | −1.04 ± 0.96 | 11.2 ± 0.86 | 21 |
| E261A | −28.27 ± 1.94 | 7.38 ± 1.36 | 10 |
Voltage dependence of current activation for homomeric wild-type (wt) KCNQ1 channels or those with alanine substituted for charged residues at positions indicated. Conductance–voltage relationships were fit to Boltzmann distributions to derive values for the midpoint of activation (V1/2) and slope (k) of the curves. n = number of independent experiments; NA = not applicable.