Figure 1.

Dimeric cytochrome b₆f complex of oxygenic photosynthesis from M. laminosus (PDB ID 2E74). (A) Polypeptide composition of the b₆f complex. Color code showing the eight known subunits of the complex: cytochrome b₆, cyan; subunit IV, pink; cytochrome f, yellow; ISP, orange; PetL, red; PetM, green; PetG, brown; PetN, wheat. (B) Prosthetic groups in the cytochrome b₆f complex are shown as sticks. The Q_p portal is highlighted as a blue cylinder. (C) The PQ molecule, which serves as the substrate of cytochrome b₆f complex-catalyzed redox reactions. Carbon atoms are shown in green, with the exception of atom C6 (white). The oxygen atoms are shown in red. (D) Overview of the p-side quinone portal, showing both Chl (green sticks) and PQ (blue sticks).