Mitochondrial ATP synthase catalyzes ATP synthesis, utilizing an electrochemical gradient of protons across the inner membrane during oxidative phosphorylation. It is composed of two linked multi-subunit complexes: the soluble catalytic core, F1, and the membrane-spanning component, Fo, which comprises the proton channel. The catalytic portion of mitochondrial ATP synthase consists of five different subunits (alpha, beta, gamma, delta, and epsilon) assembled with a stoichiometry of 3 alpha, 3 beta, and single representatives of the gamma, delta, and epsilon subunits. The proton channel likely has nine subunits (a, b, c, d, e, f, g, F6 and 8). ATP5J2 (ATP synthase, H+ transporting, mitochondrial Fo complex subunit F2) encodes the f subunit of the Fo complex. Alternatively spliced transcript variants encoding different isoforms have been identified for ATP5J2. ATP5J2 has multiple pseudogenes. Naturally occurring read-through transcription also exists between ATP5J2 and the downstream pentatricopeptide repeat domain 1 (PTCD1) gene.