Identification, Expression, and Roles of the Cystine/Glutamate Antiporter in Ocular Tissues

Figure 1

Structure of system x_c^-. System x_c^- is made up of two subunits: the heavy chain 4F2hc and the light chain xCT linked by a disulphide bond (SS). 4F2hc spans the membrane once and is responsible for anchoring the antiporter to the membrane. xCT contains 12 transmembrane domains with the C- and N-termini located intracellularly. The main function of xCT is to import cystine in exchange for glutamate at a molar ratio of 1 : 1.