Figure 1. The structure of avian cytochrome bc1 complex. An overall view of the 10-subunit complex from 2 orientations. The dimer 2-fold axis is vertical in the plane of the page. The shaded band represents the approximate location of the membrane hydrophobic phase, with the mitochondrial matrix below and inter-membrane space above. Ten subunits are shown. Subunit 11, if it exists in the chicken complex, is not present in the crystals and not consistently present in the preparation of the enzyme. This figure was made from PDB entry 1BCC, first revision after release.