Mitochondrial transporter of the positively charged amino acids ornithine, lysine and arginine, and the neutral amino acid citrulline . In addition, transports the basic amino acids histidine, homoarginine, and asymmetric dimethylarginine (aDMA), but not symmetric DMA, and the D-forms of lysine, arginine, ornithine and histidine (, ). Functions by both counter-exchange and uniport mechanisms .
Subcellular locations: Mitochondrion membrane, Mitochondrion inner membrane
Expressed in liver, testis, spleen, lung, pancreas, and small intestine and expressed poorly in other tissues.