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Fig. 3 | BMC Molecular and Cell Biology

Fig. 3

From: Mechanism of hERG inhibition by gating-modifier toxin, APETx1, deduced by functional characterization

Fig. 3

hERG inhibition by APETx1 mutants. a The primary structure of APETx1, colored as follows: positively-charged residues (K and R), blue; negatively-charged residues (D), red; hydrophobic residues (F, I, L, P, V, W, and Y), green; cysteine residues, orange; and others (G, N, S, and T), black. Three pairs of disulfide bonds are shown with orange lines. Non-mutated residues are drawn with semi-transparent gray marker to highlight the mutated residues. b The structure of APETx1 is shown as a ribbon representation with sticks depicting the mutated residues. c-e Normalized G-V curves (mean ± SEM) of hERG in the presence of 10 μM APETx1 mutants expressed by different colors and symbols. Control and WT correspond to the normalized G-V curve in the presence and absence, respectively, of 10 μM APETx1 from Fig. 1c. Based on the ΔV1/2 values, APETx1 mutants were categorized into the groups (I)-(III). f The ΔV1/2 values of 10 μM APETx1 mutants in hERG are represented as the mean values ± SEM, with the number of experiments shown in parentheses. Multiple-group comparison was performed by one-way ANOVA followed by Tukey’s test (∗, 0.01 ≤ p < 0.05; ∗∗, 0.001 ≤ p < 0.01; ∗∗∗, p < 0.001). (g) Close-up view of the hydrophobic residues that yielded group (I) mutants (boxed residues) are shown as surface representations (left) and ribbon representations with sticks depicting side chains (right). The mutated residues are shown in bold. The distance between the Cβ atoms of F15 and Y32 is 9.4 Å, and that between F15 and F33 is 10 Å

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