SLC7A9 as a heterodimer with SLC3A1 in the plasma membrane mediates the exchange of arginine (L-Arg), lysine (L-Lys), or cystine (CySS-) for leucine (L-Leu) and other neutral amino acids. The physiological concentrations of these amino acids favor neutral amino acid export and arginine/lysine/cystine import. Defects in SLC7A9 and SLC3A1 cause cystinuria. In the body, this transport process is prominent in the kidney (Mizoguchi et al. 2001).
amino acid transmembrane transporter activity of SLC7A9:SLC3A1 [plasma membrane]