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. 2004 Jun 4;558(Pt 2):417–431. doi: 10.1113/jphysiol.2004.062588

Figure 3. Steady-state activation of HERG S4 mutant channels.

Figure 3

Typical examples of currents recorded from K525Q (A) and R531Q channels (B) during 8 s steady-state activation protocols (see insets). K525Q channels start to activate at potentials < −100 mV and a depolarization to −80 mV (thick trace) resulted in over 50% activation. A depolarization to +30 mV was required to achieve 50% activation for R531Q (thick trace). C, steady-state activation curves for WT, K525Q, R528Q, R531Q, R534Q and R537Q. The V0.5 of steady-state activation was significantly shifted in a negative direction from −34.7 ± 1.6 mV for WT (n = 8) to −84.9 ± 1.4 mV for K525Q (n = 9, P < 0.05). The V0.5 of steady-state activation for all the other mutants was shifted in a positive direction (see Table 1).