A comparative study on the effect of phenobarbitol and beta-methylcholanthrene on glutathione S-transferases of rat testis.

Glutathione S-transferases (GSTs; EC, 2.5.1.18) ubiquitously distributed in all life forms, are a family of multigene and multifunctional dimeric proteins, which play a main role in drug detoxication. On purification and on electrophoresis, rat testicular glutathione S-transferases showed that it comprises of four subunits, Yc of alpha class, Yb and Ybeta of mu class and Ydelta of pi class. On chromatofocusing they were resolved into six anionic and four cationic isozymes. The substrate specificity studies and immunoblot analysis of testis proteins revealed that Ydelta of pi class GST was induced predominantly in response to phenobarbitol and Yc of alpha class and Ybeta of mu class were elevated specifically on treatment with methylcholanthrene (MC). These results show that structural variation between the two carcinogens induces different types of GST subunits. Therefore, these subunits may be used as marker proteins for specific chemical toxicity of rat testis.