FIGURE 5.
Effects of the ΔΔβ-toxins on the activity of α-toxins. Oocytes expressing DmNav1/TipE and rNav1.2/hβ1 were clamped at -80 mV, and currents were elicited by step depolarization to -10 mV. Increasing concentrations of the toxins and toxin mixtures were applied, and their relative effect on the current inactivation (sustained current) at -10 mV was determined after 50 ms. A, activity of LqhαIT (EC50 = 2.6 ± 0.2 nm) and LqhαIT in a mixture with ΔΔBj-xtrIT or ΔΔCss4 (1:50 molar ratio) on DmNav1 provide the following EC50 values: 0.6 ± 0.2 and 0.7 ± 0.2 nm, respectively. Inset, representative current traces demonstrating the effect of 25 nm ΔΔCss4 on the level of the sustained current induced by 0.5 nm LqhαIT. B, activity of Lqh2 and Lqh2 in a mixture with ΔΔBj-xtrIT and ΔΔCss4 (1:10 molar ratio) on rNav1.2 provide the following EC50 values: 13.2 ± 0.3, 44.4 ± 1, and 42 ± 1.4 nm, respectively. The maximal inhibition of inactivation by LqhαIT or Lqh2 in the absence or presence of the ΔΔβ-toxins was identical.