Figure 4.

a, Ratio between maximal leak current amplitude and maximal gating current amplitude. The ratio was constant for all mutants independently of expression level. b, Position of F244 with respect to the selectivity filter. F244 of one subunit (blue) is shown in red, as well as I429 and W434 of the neighboring subunit (light orange). Potassium in the selectivity filter is shown in green (PDB: 3LUT). c, Onset of leak current (solid black squares) compared with the gating currents (solid gray squares) and the ionic current (hollow black circles). d, Gating currents of ShakerIR-W434F-F244C with K⁺ as the dominant ion internally and NMG (left) or K (right) as dominant ion externally. e, Block of leak currents by externally applied 4-aminopyridine. f, Block of the leak current by fast (N-type) inactivation in Shaker-W434F-F244C without deletion of positions 6–46.