Figure 5 - full size

Figure 5.
Fig. 5. Schematic drawing of the closed and opened conformation of a ClC chloride channel. In the closed conformation, the ion-binding sites S[int] and S[cen] are occupied by chloride ions, and the ion-binding site S[ext] is occupied by the side chain of Glu148. In the opened conformation, the side chain of Glu148 has moved out of binding site S[ext] into the extracellular vestibule. S[ext] is occupied by a third chloride ion. Chloride ions are shown as red spheres, the Glu148 side chain is colored red, and hydrogen bonds are drawn as dashed lines.