Cystine transport is defective in isolated leukocyte lysosomes from patients with cystinosis.
The activity of a cystine transport system in lysosomes prepared from the leukocytes of patients with cystinosis was found to be deficient. In normal subjects, this system was resistant to N-ethylmaleimide and demonstrated saturation kinetics. Lysosomes from individuals heterozygous for cystinosis demonstrated a reduced maximum velocity for cystine egress from lysosomes. The rate of cystine escape from normal lysosomes was enhanced by adenosine triphosphate. The availability of normal and mutant lysosomes provides a means of investigating mechanisms of amino acid transport across lysosomal membranes.
D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D003553:Cystine / Q000378:metabolism*; D003554:Cystinosis / Q000378:metabolism*; D005033:Ethylmaleimide / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D007962:Leukocytes / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism
D002352:Carrier Proteins; D003553:Cystine; D003545:Cysteine; D005033:Ethylmaleimide