Oligomycin A (MCH 32), a dominant analog of the isomers, is an inhibitor of mitochondrial F1FO ATP synthase which inhibits oxidative phosphorylation and all the ATP-dependent processes occurring on the coupling membrane of mitochondria. It inhibits ATP synthase by blocking its proton channel (Fo subunit), which is necessary for oxidative phosphorylation of ADP to ATP. It also induces apoptosis in a variety of cell types.