Coupling of gating charge displacement to peak ionic current is diminished and more variable for HypoPP mutants than for WT channels. (A) Each symbol represents the maximal peak I_Na and associated Q_{on_max} for a separate oocyte. Lines show the best fit constrained through the origin. (B) The ensemble coupling behavior for oocytes among each channel type is summarized in a box plot. For each oocyte, the ratio I_Na/Q_{on_max} was computed. Box plots show the mean (circle), 50% level (bar), 25–75% range (box), and 10–90% range (whiskers). The coupling ratio was lower for HypoPP mutant channels than in WT (P < 0.0001). Error bars represent ± SEM.