May play a role in primary carbon metabolism and plant growth, by mediating the transport of GABA from the cytosol to mitochondria. When expressed in a heterologous system (yeast), imports Arg and Ala across the plasma membrane and exports Lys and Glu, but does not transport proline. A number of isoforms are produced. According to EST sequences. Expressed in roots, rosette leaves, stems, cauline leaves, flowers and siliques. No visible phenotype under normal growth conditions, but mutant plants grown on medium without sucrose show strong decrease in root growth and plants grown on soil under low light intensity have reduced rosette leaf expansion. Belongs to the amino acid-polyamine-organocation (APC) superfamily. Amino acid/choline transporter (ACT) (TC 2.A.3.4) family.