Adenosine triphosphatase from rat liver mitochondria. III. Subunit composition

Preparations of mitochondrial ATPase from rat liver mitochondria contain five classes of polypeptide chains. Consistent with previous results, the three major classes of polypeptide chains, designated subunits A,B, and C, have apparent molecular weights of 62,500, 57,000, and 36,000, respectively, as determined by gel electrophoresis in sodium dodecyl sulfate. These subunits have been isolated in purified form. They comprise approximately 97% of the mass of the enzyme preparation and are present in the enzyme complex in the stoichiometry A₃B₃C. The two minor classes of polypeptide chains have molecular weights of 12,500 and approximately 7,500 as determined by gel electrophoresis in sodium dodecyl sulfate. They appear to comprise less than 3% of the mass of the enzyme preparation.