Associates with SLC3A1 to form a functional transporter complex that mediates the electrogenic exchange between cationic amino acids and neutral amino acids, with a stoichiometry of 1:1 ( , ). Has system b(0,+)-like activity with high affinity for extracellular cationic amino acids and L-cystine and lower affinity for intracellular neutral amino acids ( ). Substrate exchange is driven by high concentration of intracellular neutral amino acids and the intracellular reduction of L-cystine to L-cysteine . Required for reabsorption of L-cystine and dibasic amino acids across the brush border membrane in renal proximal tubules.
Subcellular locations: Apical cell membrane, Cell membrane
Expressed in the brush border membrane in the kidney (at protein level). Kidney, small intestine, liver and placenta.