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. The two complexes are linked by a central stalk and a peripheral stalk. During catalysis, ATP synthesis in the catalytic domain of F1 is coupled, via a rotary mechanism of the central stalk subunits, with proton translocation across the membrane. ATP5I, also known as mitochondrial ATP synthase subunit E or ATP5K, is a 69 amino acid protein member of the ATPase E subunit family. Localized to the inner membrane of the mitochondria, ATP5I is a part of the F0 complex.