Table 1. Macroscopic Open Channel Currents (Itail0) of Vacuolar Excised Outside-Out Patches Expressing ALMT9, ALMT4 S382A, and ALMT4 Wild Type Were Fitted by a Boltzman Function (Equation 3)
Parameter of Gating and Current KineticsALMT9 (n = 7)ALMT4 Wild Type (n = 8)ALMT4 S382A (n = 8)
Itail0 max (pA)121 ± 38a142 ± 16a256 ± 18b
V1/2 (mV)−90 ± 10a−63 ± 4b−67 ± 1b
zg0.7 ± 0.10.7 ± 0.020.7 ± 0.01
τActivation1.3 ± 0.21.3 ± 0.11.2 ± 0.4
τDeactivation0.1 ± 0.02a0.4 ± 0.04b0.4 ± 0.1b
R0.2 ± 0.02a0.7 ± 0.01b0.8 ± 0.1b
  • From the fit, the maximal Itail0 (Itail0 max), the half-maximal activation voltage (V1/2), and the gating charge (zg) were derived. The time-dependent current proportion of activating currents and deactivating tail currents were fitted by standard exponential functions to derive activating (τActivation) and deactivating (τDeactivation) time constants. The rectification rates (R) were derived by dividing the steady state time-dependent conductance at the deactivating tail voltage of +60 mV by the conductance at the activating voltage of −120 mV. Data are averages ± se. Significant differences were tested for each parameter by ANOVA followed by Holm-Sidak multiple comparison (P ≤ 0.001) and are indicated by different letters.