Identification of a hepatic plasma membrane glutathione S-transferase activated by N-ethylmaleimide.
Rat liver plasma membranes exhibit membrane-bound glutathione S-transferase activity. The specific activity in isolated canalicular membranes was 83 +/- 8 mU/mg protein and 50 +/- 3 mU/mg protein in the sinusoidal membranes. Whereas microsomal and outer mitochondrial glutathione S-transferases were stimulated seven and four-fold with N-ethylmaleimide, respectively, the plasma membrane activity was activated two-fold. Western blot analysis, using an antibody against the microsomal glutathione S-transferase, shows the presence of a 17 kDa protein in canalicular and sinusoidal membrane fractions. The antibody reaction was about three-fold higher in the canalicular compared to the sinusoidal membrane fraction. These data support the conclusion that the plasma membrane glutathione S-transferase is closely related to the microsomal and outer mitochondrial membrane enzyme.
Institut für Physiologische Chemie I, Heinrich-Heine-Universität Düsseldorf, Germany.
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Horbach
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Sies
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Akerboom
D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005033:Ethylmaleimide / Q000494:pharmacology*; D005979:Glutathione Peroxidase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D008930:Mitochondria, Liver / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar; D013439:Sulfhydryl Reagents; D013997:Time Factors
D013439:Sulfhydryl Reagents; D005979:Glutathione Peroxidase; D005982:Glutathione Transferase; D005033:Ethylmaleimide