ATP5J2 is part of the complex F0 domain of the mitochondrial ATP synthase. This produces ATP from ADP in the presence of a proton gradient across the membrane which is generated by electron transport complexes of the respiratory chain. It is composed of two complexes: the soluble catalytic core, F1, and the membrane-spanning component, Fo, which comprises the proton channel. ATP5J2 encodes the f subunit of the Fo complex. There are 2 isoforms produced by alternative splicing.