title: Dinitrophenyl glutathione efflux from human erythrocytes is primary active ATP-dependent transport.
abstract: Dinitrophenyl S-glutathione is accumulated by inside-out vesicles made from human erythrocytes in a process totally dependent on ATP and Mg2+. The vesicles were shown to accumulate dinitrophenyl S-glutathione against a concentration gradient. The vesicles were able to concentrate this glutathione derivative even in the absence of membrane potential. This indicated that the ATP-dependent uptake of dinitrophenyl S-glutathione by inside-out vesicles represented an active transport process. Neither extravesicular EGTA nor intravesicular ouabain inhibited the transport process, indicating that neither the Ca2+-ATPase nor the Na+, K+-ATPase were involved. These results indicated that dinitrophenyl S-glutathione uptake by inside-out vesicles probably represented primary active transport. The uptake of dinitrophenyl S-glutathione was a linear function of time (up to 5 h) and vesicle protein. The rate of uptake was optimal between pH 7.0 and 8.0 and at 37 degrees C. The Km values determined for dinitrophenyl S-glutathione and ATP were 0.29 mM and 1 mM, respectively. The transport process was completely inhibited by vanadate and by p-hydroxymercuribenzene sulphonate and inhibited to a lesser extent by N-ethylmaleimide. GTP could efficiently substitute for ATP as an energy source for the transport process, but CTP and UTP were comparatively much less effective.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D001693:Biological Transport, Active / Q000187:drug effects; D001798:Blood Proteins / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D005978:Glutathione / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology
chemical_list: D001798:Blood Proteins; D013439:Sulfhydryl Reagents; D014639:Vanadium; C030190:S-(2,4-dinitrophenyl)glutathione; D014638:Vanadates; D000255:Adenosine Triphosphate; D005978:Glutathione; D008274:Magnesium