ANT has long been thought to function asymmetrically as a homodimer of subunits in the inner mitochondrial membrane. The dimer was thought to be a gated pore through which ADP and ATP were exchanged between the mitochondrial matrix and the cytoplasm. The dimer hypothesis was first challenged when the three-dimensional structure of ANT was discovered to be a monomer. Further work has shown that ANT functions a monomer in detergents and in mitochondrial membranes.
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^Bamber L, Slotboom DJ, Kunji ER (August 2007). "Yeast mitochondrial ADP/ATP carriers are monomeric in detergents as demonstrated by differential affinity purification". J. Mol. Biol.371 (2): 388–95. doi:10.1016/j.jmb.2007.05.072. PMID17572439.