Replacement of Trp²⁰⁷ greatly accelerates hH_V1 opening. The activation time constant, τ_act, was obtained by fitting rising currents to a single exponential. All measurements were done at symmetrical pH 7.0 but include both whole-cell and excised inside-out patch data. Error bars represent mean ± SEM, with n = 7, 9, and 8 for W207F, W207S, and W207A, respectively; WT includes five cells and seven inside-out patches.