Mitochondrial ATP synthases (ATPases) transduce the energy contained in membrane electrochemical proton gradients into the energy required for synthesis of high-energy phosphate bonds. ATPases contain two linked complexes, F1, the hydrophilic catalytic core, and F0, the membrane-embedded protein channel. F1 consists of three ? chains and three ? chains, which are weakly homologous, as well as one ? chain, one ? chain and one ? chain. F0 consists of three subunits, a, b and c. The ? chain of F1 is a regulatory subunit that contains 509 amino acids. Mitochondrial ATPase ? chain (ATP5A) localizes to the mitochondria and catalyzes ATP synthesis.