Figure 1
The structure of the potassium ion channel KcsA (PDB entry 1k4c). (a) The overall structure of KcsA is shown in cartoon format. For clarity, only two of the four subunits that make up a complete ion channel are shown in cyan and magenta, with potassium ions shown as orange spheres and water molecules shown as red spheres. (b) A close-up view of the selectivity filter (SF) of KcsA showing the four binding sites located within the SF. In the presence of four subunits, each binding site is coordinated to eight O atoms found in the backbone carbonyl atoms of Thr75, Val76, Gly77 and Tyr78 and the hydroxyl O atom of Thr75. |