Fig. 9.
Leveraging heteromeric channel composition to lock open KCNQ2/3. a Averaged traces showing effects of RTG, IVA, and MTX alone or in combination, doses as indicated, on homomeric KCNQ2–5 channels (n = 4–11). Voltage protocol as in Fig. 1d. b–d Analysis of traces as in a: b tail current; c G/Gmax; d current fold-change versus voltage; compounds and combinations color-coded as in a. n = 4–11. e, f Effects of high-dose RTG + MTX + IVA on KCNQ2/3 versus KCNQ3* held at −120 mV for 25 s. e Representative traces; f mean peak (0.5 s) versus steady-state (25 s) current. **p < 0.01; n = 4. Box and whisker plots: box range, SEM, coefficient of 1; whisker range 5–95%, coefficient of 1.5. g Model summarizing findings. Squares represent subunits within tetrameric KCNQ2/3 channels (yellow, KCNQ2; pale blue, KCNQ3). h Possible distinct binding positions of RTG, IVA, and MTX in one binding site in KCNQ3 (left) versus a lower-positioned RTG binding site (center) that would overlap with binding sites for IVA and RTG (right), predicted by SwissDock using a chimeric KCNQ1–KCNQ3 structure model. Red, KCNQ3-W265; magenta, IVA; blue, MTX; yellow, RTG. Space-filling omitted from molecules in right panel for clarity. i Further possible poses RTG (yellow, no spacefill) that would overlap with IVA (magenta) and MTX (blue) in KCNQ3 chimera model as predicted by SwissDock. All error bars indicate SEM. All comparisons by one-way ANOVA