HUMAN GLUTATHIONE S-TRANSFERASES

1. Multiple forms of glutathione S-transferase (GST) isoenzymes presen t in human tissues are dimers of subunits belonging to three distinct gene families namely alpha, mu and pi. Only the subunits within each c lass hybridize to give active dimers. 2. These subunits are differenti ally expressed in a tissue-specific manner and the composition of glut athione S-transferases in various tissues differs significantly. 3. Mi nor GST subunits not belonging to these three classes are also present in some tissues. 4. An ortholog of rat GST 8-8 and mouse mGSTA4-4 is selectively expressed in some human tissues including bladder, brain, heart, liver, and pancreas. This isoenzyme designated as GST 5.8 expre sses several fold higher activity towards 4-hydroxy-2,3-trans-nonenal as compared to the routinely used substrate 1-chloro-2,4-dinitrobenzen e.