Fig. 1.
Ion binding and conductance in NaK. (A) The selectivity filter structure of NaK in complex with K+ ions (PDB 3E8H). The 2Fo - Fc map contoured at 1.5σ shows the electron density (blue mesh) of water and K+ represented by red and green spheres, respectively. (B) Superimposition of the NaK filter structure (green) with that of KcsA (magenta, PDB 1K4C). Two diagonally opposite subunits are shown for clarity. (C) Single channel traces of NaK at ± 20 and ± 80 mV and its I-V curve. Currents were recorded using giant liposome patch clamping with 150 mM NaCl and 150 mM KCl in the pipette and bath solutions, respectively. The same method was used in the recordings of all NaK mutants.