Mitochondrial arginine transporter that catalyzes the counter-exchange of arginine with lysine, ornithine, arginine and histidine. Substrate preference in reconstituted proteoliposomes is arginine > lysine > ornithine > histidine. May be involved in the delivery of arginine, released from seed reserves, to mitochondrial arginase and the export of ornithine. Inhibited by mercuric chloride. Optimum pH is 7.0-9.0. High expression in flowers and siliques. Lower expression in leaves and stems. Belongs to the mitochondrial carrier (TC 2.A.29) family.