<P> E. coli ATP synthase is the simplest known form of ATP synthase, with 8 different subunit types . </P> <P> Yeast ATP synthase is one of the best - studied eukaryotic ATP synthases; and five F, eight F subunits, and seven associated proteins have been identified . Most of these proteins have homologues in other eukaryotes . </P> <P> In plants, ATP synthase is also present in chloroplasts (CF F - ATP synthase). The enzyme is integrated into thylakoid membrane; the CF - part sticks into stroma, where dark reactions of photosynthesis (also called the light - independent reactions or the Calvin cycle) and ATP synthesis take place . The overall structure and the catalytic mechanism of the chloroplast ATP synthase are almost the same as those of the mitochondrial enzyme . However, in chloroplasts, the proton motive force is generated not by respiratory electron transport chain but by primary photosynthetic proteins . </P> <P> The ATP synthase isolated from bovine heart mitochondria (Bos taurus) is, in terms of biochemistry and structure, the best - characterized ATP synthase . Beef heart is used as a source for the enzyme because of the high concentration of mitochondria in cardiac muscle . </P>

Where are atp synthase complexes located in plant cells