xCT, encoded by the gene SLC7A11, is a member of the heterodimeric amino acid transporter family. Proteins within this family are linked to one another via a disulphide bond to form heterodimers consisting of one light subunit and one heavy subunit (1). These heterodimers facilitate the transport of amino acids across cell membranes. The light subunit xCT dimerises with the heavy subunit 4F2hc and the role of the xCT-4F2hc heterodimer, also known as system Xc-, is to couple the release of one molecule of intracellular glutamate to the uptake of one molecule of extracellular cystine (2).
