Fig. 3.

Phosphorylation-induced SSI shift is similar in ΔK1500 and WT. (A) Representative current traces for ΔK1500 NM (light green) and ΔK1500 phY (dark green) constructs. (B) SSI (Left) and activation (Right) curves of indicated constructs. (C) Late currents (Upper) and inactivation rates (Lower) for indicated constructs. Data are shown as mean ± SD in B and C; n = 6 to 10; data were compared using unpaired two-tailed Student’s t test; ns (not significant) P > 0.05, *P ≤ 0.05, ***P ≤ 0.001, and ****P < 0.0001. (D) Contact frequency of Y1495 and IFM particle with neighboring residues. (E) Conformation of the IFM particle in its binding site after 200 ns of MD simulation. I1485 increases its contacts with DIII-S6 residues. IFM side chains highlighted in orange. (F) Free energy profile of IFM unbinding using the distance between the COM of N1659 in the DIV-S5 helix and F1486 in the IFM particle as a reaction coordinate. The binding energy of the IFM particle for the ΔK1500 phY system is similar to that of WT phY.