The terminal steps of oxidative phosphorylation include transport of phosphate and ADP into the mitochondrial matrix, synthesis of ATP in the matrix, and transport of the product ATP into the cytosol where it can be utilized to perform cellular work. Three nuclear genome encoded membrane proteins, namely, the phosphate carrier (PHC), the adenine nucleotide carrier (ANT), and the ATP synthase complex, consisting of at least 13 individual subunits, catalyze these reactions. The locations of the alpha and gamma subunits of the mitochondrial ATP synthase complex and the mitochondrial phosphate carrier, PHC, on human chromosomes were determined using cloned rat liver cDNA as probes. Human homologues of the alpha subunit are on chromosomes 9 and 18, the gamma subunit are on chromosomes 10 and 14, and the PHC was localized to chromosome 12.