Figure 2.

Shaker Kv channel mutants with intact voltage-dependent gating. (A) Families of ionic current records for Wt and five mutant Shaker channels. For Wt Shaker, holding voltage was −90 mV, tail voltage was −70 mV, and depolarizations were from −70 to 50 mV, in 10-mV increments. For S479W, holding voltage was −100 mV, tail voltage was −100 mV, and depolarizations were from −100 to 90 mV, in 10-mV increments. For L472A holding voltage was −100 mV, tail voltage was −70 mV, and depolarizations were from −70 to 40 mV, in 10-mV increments. For Y483D, holding voltage was −90 mV, tail voltage was −70 mV, and depolarizations were from −70 to 40 mV, in 10-mV increments. For V476A holding voltage was −100 mV, tail voltage was −130 mV, and depolarizations were from −90 to 40 mV, in 10-mV increments. For F484D, holding voltage was −100 mV, tail voltage was −80 mV, and depolarizations were from −80 to 50 mV, in 10-mV increments. In all cases, depolarizations were 50 ms in duration. Linear capacity and background conductances were identified and subtracted by blocking the Shaker channel with Agitoxin-2. (B) G-V relations for Wt and five mutants. Normalized tail current amplitudes, measured at voltages indicated in A, are plotted versus the voltage of the preceding depolarization. Smooth curves are single Boltzmann fits to the data with parameters as follows: Wt: V₅₀ = −31.8 mV, z = 4.1; V476A: V₅₀ = −52.2 mV, z = 6.1; F484D: V₅₀ = −49.2 mV, z = 4.2; Y483D: V₅₀ = −40.4 mV, z = 4.6; L472A: V₅₀ = −4.7 mV, z = 3.3; S479W: V₅₀ = 87.7 mV, z = 0.7.