Mitochondrial ornithine-citrulline antiporter (, ) (Probable). Catalyzes the exchange between cytosolic ornithine and mitochondrial citrulline plus an H(+), the proton compensates the positive charge of ornithine thus leading to an electroneutral transport. Plays a crucial role in the urea cycle, by connecting the cytosolic and the intramitochondrial reactions of the urea cycle (, ) (Probable). Lysine and arginine are also transported by the antiport mechanism  (Probable). In addition, catalyzes an electroneutral exchange of ornithine or lysine for H(+), a reaction driven by the pH gradient across the inner membrane (By similarity).
Subcellular locations: Mitochondrion inner membrane, Mitochondrion membrane
Highly expressed in liver, pancreas, testis, lung and small intestine. Lower levels are detected in spleen, kidney, brain and heart.