Purification of rat liver plasma membrane glutathione transferase

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Abstract
Glutathione transferases purified from plasma membrane and microsomal fractions from rat liver share similar enzymic properties. The activity of both proteins with 1‐chloro‐2,4‐dinitrobenzene can be stimulated about 10–15‐fold by N‐ethylmaleimide. No activation is observed using p‐nitrobenzylchloride as a substrate.The enzymes are immunologically related as indicated by Western‐blot analysis using antibodies against the microsomal glutathione transferase or against a synthetic peptide corresponding to the amino acid positions 55–64 of microsomal glutathione transferase. Isolated plasma membrane and microsomal glutathione transferases possess the same amino‐terminal amino acid sequence and digestion with different proteases results in identical fragment patterns as displayed by SDS/PAGE. These data suggest that plasma membrane and microsomal glutathione transferase are identical proteins.