Lateral Distribution of the Cytochrome b(6)/f and Coupling Factor ATP Synthetase Complexes of Chloroplast Thylakoid Membranes.

We have visualized directly the distribution of the cytochrome b(6)/f and coupling factor ATP synthetase complexes in thylakoid membranes of embedded, thin-sectioned, intact chloroplasts by using rabbit antibodies directed against each complex, followed by ferritin-conjugated goat anti- (rabbit immunoglobulin G) antibodies. The labeling patterns indicate that in spinach (Spinacia oleracea) chloroplasts the cytochrome b(6)/f complex is distributed laterally throughout both stacked grana and unstacked stroma membrane regions, whereas the coupling factor ATP synthetase complex is found exclusively in stroma thylakoids and in the marginal and end membranes of grana.