Figure 13.

Comparison of deactivation time constants for different β3b constructs. In A, deactivation time constants (τ_d) obtained from single exponential fits to the tail current time course (Fig. 7) are plotted as a function of repolarization potential for currents from α subunit alone for 0 (⋄), 1 (♦), 4 (□), 10 (▪), 60 (○), and 300 (•) μM. In B, τ_d is plotted as a function of voltage for α + β3b currents with symbols as in A. In C, τ_d is plotted as a function of voltage for α + β3b-ΔC currents. In D, τ_d is plotted as a function of voltage for α + β3b-ΔN currents. In E, the deactivation rate measured at −80 mV is plotted as a function of Ca²+ for each construct (α, ⋄; α + β3b, ♦; α + β3b-ΔC, ○; and α + β3b-ΔN, •). In F, the deactivation rate measured at −160 mV is plotted as a function of Ca²+ with symbols as in E. Current deactivation for α alone is ∼1.5–2-fold faster than for currents resulting from any β3b construct.