Electron micrographs coupling factor

Few studies have been made on the specificity of plant membrane proteins for lipids. Only three amphiphilic membrane proteins have been isolated and purified from plants. They are the coupling factor ATPase complex from chloroplasts (Younis et al., 1977), cytochrome/(Nelson and Racker, 1972), and plastocyanin (Ramshaw et al., 1974). The lipid-free coupling factor is a five-subunit ATPase which is catalytically active. One of the subunits, designated the 8 subunit, can be removed, and stimulation of photophosphorylation in a lipid vesicle system depends on this subunit (Younis et al., 1977). The 8 subunit is thought to represent the stalk seen in electron micrographs of negatively stained membranes. 

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