Exchange of the carboxy termini downstream of the linker between helices A and B retains the differential P_o values and PIP₂-apparent affinities of the wt channels. The third chimera pair between Kv7.3 and Kv7.4 was created by exchange of the carboxy termini downstream of the end of the linker between helices A and B. Shown are single-channel patch-clamp recordings from the Kv7.3/7.4_C-3 (A) or Kv7.4/7.3_C-3 (B) chimeras obtained in the cell-attached (top) or excised inside-out (bottom) configurations at 0 mV. The indicated concentrations of diC8-PIP₂ were perfused over the inside-out patches. The insets above the current records show the topography and chimera junctions of the channel subunits. (C) Bars summarize the P_o at 0 mV in cell-attached patches for these chimeras. (D) Plotted are the summarized P_o values at 0 mV for the chimeras in inside-out configuration obtained over a range of diC8-PIP₂ concentrations. The data were fit by a Hill equation of the form and parameters given in the text.