Figure 18-14

Membrane Region:

Redox Centers:
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X-ray structure of the yeast Complex III homodimer in complex with cytochrome c and the inhibitor stigmatellin. The view is perpendicular to its 2-fold axis and parallel to the membrane with the matrix below. The nine different subunits in each protomer of Complex III, which collectively have 12 transmembrane helices, are drawn in ribbon form and are differently colored with cytochrome b pale yellow, cytochrome c1 light purple, the ISP tan, Core 1 cyan, and Core 2 orange. The bound cytochrome c is pink. The four different heme groups, the [2Fe–2S] cluster, and stigmatellin are drawn in space-filling form with heme C green, stigmatellin C magenta, N blue, O red, S yellow, and Fe red-brown. Note that only one cytochrome c is bound to the homodimeric Complex III. [Based on an X-ray structure by Carola Hunte, Max Planck Institute for Biophysics, Frankfurt am Main, Germany. PDBid 1KYO.]