Figure 4.
Ionic and gating currents recordings for mutations at p4, p5, and p7 in the Shaker and Kv1.2 channels. (A) Family of ionic currents for Shaker-IR Y445F (p5). (B) Family of ionic currents for Kv1.2 Y377F (p5). (C) G–V relations for Kv1.2 and Kv1.2 Y377F (p5). Normalized G–V relations were obtained by measuring the amplitude of the tail current and normalizing to the maximum elicited following depolarization to +50 mV. n = 6 for Kv1.2 Y377F (p5) and n = 7 for Kv1.2. (D) Currents in response to long (20 s) pulses from −20 to +60 mV in 20-mV steps for Kv1.2 Y377F (p5). The current slowly decays in amplitude as a result of a slow inactivation process. The red curves are the fits of a double-exponential function to the current traces. (E) Inactivation time constants are plotted as a function of voltage for Kv1.2 and Kv1.2 Y377F (p5). The filled square symbols are slow time constants, and the filled circle are fast time constants. n = 7 for Kv1.2, n = 6 for Kv1.2 Y377F (p5), and n = 5 for Kv1.2 Y377F+V381T (p5/p7). (F) Family of ionic currents for Kv1.2 Y377F/V381T (p5/p7). (G) Family of gating currents for Kv1.2 Y377A (p5). (H) Family of ionic currents for Kv1.2 S371T/Y377F (p4/p5). (I) Family of ionic currents for Kv1.2 S371T/Y377F/V381T Kv1.2 (p4/p5/P7). All data are mean ± SEM.