Part of the ABC transporter complex TcyJKLMN involved in L-cystine import. Probably responsible for the translocation of the substrate across the membrane (Probable). Is also involved in cystathionine, djenkolate, and S-methylcysteine transport. The complex is composed of two ATP-binding proteins (TcyN), two transmembrane proteins (TcyL and TcyM) and two solute-binding proteins (TcyJ and TcyK). More strongly expressed in the presence of methionine than in the presence of sulfate. Belongs to the binding-protein-dependent transport system permease family.