The presence of VSD is required for a functional permeation pathway even if access to the pore is granted by proline substitutions in S6. (A) KV10.1 pore viewed from the intracellular side. The first helix of the C linker is indicated in dark red, Q476 in blue, Q477 in green, the S4–S5 linker in magenta, and the C-terminal S4 in yellow (the part of the helix above the innermost voltage-sensing arginine is not depicted). (B) Representative current traces of Q476P and Q477P mutants in the full-length channel recorded with the indicated voltage protocol. (C) The corresponding normalized, mean current values ± SEM plotted against voltage (n = 5–11). (D) Representative currents from oocytes expressing the isolated PD (G348-C stands for the PD sequence starting from Gly348 and ending at the C terminus), Q477P mutant in the isolated PD, Y347 split and Y347 split carrying Q477P mutation alone, or in combination with additional VSD mutations. (E) Mean current values ± SEM plotted against voltage (n = 7–10; without normalization). (F) Normalized conductance values plotted against voltage. The data represent mean ± SEM (n = 6–10), and the curves are parabola fits for Q477P mutants and a Boltzmann fit for the wild type.
