Mediates uptake of L-cystine, the oxidized form of L-cysteine. Although it is more specific for L-cystine, it could also transport a much broader range of amino acids and sulfur compounds including S-methylcysteine. More strongly expressed in the presence of methionine than in presence of sulfate. Strongly inhibited by seleno-DL-cystine. Belongs to the dicarboxylate/amino acid:cation symporter (DAACS) (TC 2.A.23) family.