GLUTATHIONE S-TRANSFERASES IN RAT TESTIS MICROSOMES - COMPARISON WITHLIVER TRANSFERASE

Glutathione S-transferases in testis microsomes were purified from rat s and compared with the liver microsomal transferase. When microsomal fractions were prepared from rat testis by the same method as used for liver microsomes, testis microsomal glutathione S-transferase activit y was increased a-fold by N-ethylmaleimide as compared to a 7-fold inc rease in that of the liver transferase. In contrast to the single glut athione S-transferase in liver microsomes, at least three isozymes of glutathione S-transferase were separated from testis microsomes on hyd roxylapatite column chromatography. The major fraction exhibiting glut athione S-transferase activity from the testis microsomes was shown to contain a member of the Mu family. The second fraction with transfera se activity contained one of the Alpha class, and the third and smalle st fraction was found to contain the liver microsomal form of glutathi one S-transferase. Since the GSH S-transferase of the Mu family is pre sent in the cytosol, we isolated the GSH S-transferase from testis cyt osol, it being suggested that the major GSH S-transferase in testis mi crosomes is the cytosolic transferase. These results indicate that tes tis microsomes contain mainly the cytosolic form of glutathione S-tran sferase, and that the activity of the liver microsomal form of the tra nsferase is very low.