Fig. 2.

Model of cyanobacterial membrane system and the distribution of electron transport complexes in the membranes. Left, thin-section electron microscopy image of a Synechococcus 7942 cell. The thylakoid membranes of Synechococcus are organized in a series of regular, concentric layers along the length of the cell. Right, distribution of the major components of cyanobacterial electron transport pathways in the cytoplasmic and thylakoid membranes. Respiratory electron transport components (blue) are located in both cytoplasmic and thylakoid membranes. The thylakoid membrane houses complexes from both photosynthetic (green) and respiratory electron transport chains. Abbreviations: ATPase — ATP synthase, cyt bd — cytochrome bd oxidase, NDH-1 and -2 — type 1 and II NADPH dehydrogenase, terminal oxidase — cytochrome terminal oxidase.