Cysteamine prevents cystine accumulation in lysosomes (C. Brétaudeau). In healthy patients, cystine is exported from lysosomes by a specific protein, cystinosin. In cystinotic cells, cystinosin is inefficient and cystine accumulates into cells. The specific treatment, cysteamine replaces one cysteine creating a mixed disulfide molecule, and allowing it to exit the lysosome by an other transmembrane protein, PQLC2.