The position of the other three equivalent KCNE1-binding sites in the tetrameric KCNQ1 channel is indicated. KCNE1 is bound in a cleft between the VSD and PD and makes contacts to three KCNQ1 subunits. ( C) View of the KCNQ1-KCNE1 models from the extracellular side. The approximate position of the membrane bilayer is indicated by horizontal lines and the extracellular and intracellular side are labeled EXT and INT, respectively. Residues F57, T58, and L59 are drawn as spheres and colored light blue, red, and dark blue, respectively. KCNQ1 is represented with cylindrical helices and KCNE1 is depicted as yellow ribbon. ( B) Side view of the KCNQ1-KCNE1 docking models. KCNE1 was docked to KCNQ1 with the VSD/PD in the resting/closed (RC) or activated/open (AO) conformation. The S4 helix (with positive gating charges “+”) and S4-S5L, which connects S4 to the PD, are shown as green and blue cylinders, respectively. ( A) Schematic cartoon depicting the functional states of the VSD (green box) and PD (blue box) in the KCNQ1-KCNE1 models. ![]() ![]() (Control n = 8, DTT n = 6, Cu-phen n = 6) Solid lines represent fits with a Boltzmann function ( I tail/ I tailmax = (1 - I Bottom) / (1+exp) + I Bottom) and the parameters of the fit are summarized in Supplementary file 1 – Table 1. n = 7) ( C) Average I-V relationships and activation curves of CHO-K1 cells expressing KCNQ1 I274C and KCNE1 V47C with and without DTT or Cu-phenanthroline in the bath solution. n = 7) ( B) Average I-V relationships and activation curves of currents measured from CHO-K1 cells transiently expressing KCNQ1 V141C and KCNE1 V47C, which were exposed to control bath solution, DTT, or Cu-phenanthroline (Cu-phen.), respectively. Cells were exposed to control bath solution, DTT, or Cu-phenanthroline (Cu-phen.), respectively. ![]() ( A) Average I-V relationships and activation curves of currents recorded from CHO-K1 cells transiently expressing KCNQ1 I274C and KCNE1 L48C.
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