Transport system xc− found in plasma membrane of cultured mammalian cells is an
exchange agency for anionic amino acids with high specificity for anionic form of cystine and
glutamate. We have isolated cDNA encoding the transporter for system xc− from mouse
activated macrophages by expression in Xenopus oocytes. The expression of system xc−
activity in oocytes required two cDNA transcripts, and the sequence analysis revealed that
one is identical with the heavy chain of 4F2 cell surface antigen (4F2hc) and the other is a …