Figure 4. Example of energy-minimized structure simulation of lidocaine (A) and tetracaine (B) docked in the open KcsA structure (PDB entry 3PJS) with S₁/S₃ K⁺ occupancy of the selectivity filter. Front subunit is removed for clarity. Right panel is an enlargement of the docked LA molecule zoomed from the left panel. In this and subsequent structure figures, the side chains of Thr75, Ile100 and Phe103 residues as well as the backbone carbonyls of Thr75 are shown as thin sticks. LA molecules and water molecules in the selectivity filter are shown as thick sticks. Potassium ions are shown as yellow spheres.