title: Cystine exodus from normal leucocytes is stimulated by MgATP.
abstract: Cystine exodus from partially purified granular fractions of normal leucocytes is stimulated by MgATP. N-Ethylmaleimide, an inhibitor of the lysosomal H+-translocating ATPase, eliminated the stimulated exodus, but had no effect on basal exodus. As the initial content of cystine was increased, the initial velocity of both the basal and ATP-stimulated egress increased. However, as saturation with substrate was approached, the ATP stimulation disappeared leaving only the N-ethylmaleimide-insensitive basal exodus. The increased initial velocity in the presence of ATP may represent improved binding of cystine to the partially saturated inner transporter as a result of conformational or charge optimization brought about by the action of the H+-translocating ATPase.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D003553:Cystine / Q000097:blood*; D006801:Humans; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism*; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism
chemical_list: D003553:Cystine; D000255:Adenosine Triphosphate