title: pH effects on cystine transport in lysosome-rich leucocyte granular fractions.
abstract: Inhibitors of lysosomal acidification (4,4'-di-isothiocyanostilbene-2,2'-disulphonate, NN'-dicyclohexylcarbodi-imide, carbonyl cyanide m-chlorophenylhydrazone, NH4Cl and methylamine hydrochloride) did not alter cystine egress or countertransport in polymorphonuclear-leucocyte lysosome-rich granular fractions at pH 7.0. Together, 2 mM-MgCl2/MgATP and 90 mM-KCl stimulated cystine egress 2-fold, but this effect also was not influenced by inhibitors of ATP-dependent lysosomal acidification. MgCl2/MgATP stimulated cystine transport at pH 5.5, but the effect also occurred with MgCl2, MgSO4 or MnCl2 alone, was prevented by chelation, and was not seen with NaATP; therefore, it was considered a bivalent-cation, not an ATP, effect. Proton-pump-mediated acidification of lysosomes does not appear to be required for cystine transport in normal polymorphonuclear-leucocyte granular fractions, as reported for lymphoblast lysosomes.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D001692:Biological Transport; D003553:Cystine / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism*; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D003553:Cystine; D000255:Adenosine Triphosphate; D008274:Magnesium