FIGURE 7.

Kinetic analysis for tandem dimers. A, representative current traces of tandem dimers. Currents were recorded with step pulses in the range of −60 to +120 mV for 1 s with 10-mV increments. Red traces, currents recorded at +100 mV. Scale bars, 100 pA in each mutant. B and C, comparison of the activation (B) and deactivation (C) time constants of the tandem constructs and the delC channel. Bars, means ± S.E. (error bars) (n = 5–6). Means in each mutant were compared statistically with the I-delC mutant using the Tukey-Kramer test (***, p ≤ 0.001; **, p ≤ 0.01; *, p ≤ 0.05; N.S., p > 0.05; ctrl., control). Two exponential components of the activation kinetics were analyzed in the I-W and W-I tandem dimers. We note that the deactivation kinetics in the I-I, I-W, W-I, delC, and I-delC (W203I delC) constructs were so fast that two components were inseparable.