Figure 7. Stereo view of the Qo site and the ef linker peptide. Above, the view is zoomed out to show the region in the context of cytochrome b (pink and red), cytochrome c₁ (blue), and the Rieske protein (green). Below, the view is zoomed in to make details visible. The transmembrane helices E and F of cytochrome b, as well as the connecting ef linker (residues 246 to 288) are red while the rest of cytochrome b is pink. The binding position of Qo site inhibitors is shown by the yellow and red model of stigmatellin behind and to the right of the descending arm of the ef linker. Behind this inhibitor the cd1 and C helices come together at an acute angle. Purple spheres are the iron atoms in the low potential cytochrome b heme and in the Rieske ironsulfur cluster. Some residues dicussed in the text are labeled.