Surprisingly, while both cystinosin and cystinosinLKG interacted with NHE3, rescue of the expression of CTNS, but not CTNS-LKG, was able to restore normal trafficking of NHE3 in cystinosis patient PTCs and improve sodium and albumin uptake in CTNS-deficient PTC lines. The gene discussed is SLC9A3; the disease is cystinosis.