Part of the ABC transporter complex TcyJLN involved in L-cystine import. This high affinity cystine transporter is involved in resistance to oxidative stress by forming a L-cysteine/L-cystine shuttle system with the EamA transporter, which exports L-cysteine as reducing equivalents to the periplasm to prevent the cells from oxidative stress. Exported L-cysteine can reduce the periplasmic hydrogen peroxide to water, and then generated L-cystine is imported back into the cytoplasm via the TcyJLN complex. Functions at low cystine concentrations. The system can also transport L-cysteine, diaminopimelic acid (DAP), djenkolate, lanthionine, D-cystine, homocystine, and it mediates accumulation of the toxic compounds L-selenaproline (SCA) and L-selenocystine (SeCys). Responsible for the translocation of the substrate across the membrane (Probable).