Regulation of glutathione S-transferase mRNAs by phenobarbital and 3-methylcholanthrene: analysis using cDNA probes

Using antibody directed against glutathione S-transferase B (YaYc heterodimer) and glutathione S-transferases A and C (Yb homodimers), we have purified the corresponding mRNAs by polysome immunoprecipitation. These mRNAs have been utilized to synthesize high specific activity cDNA probes which have been used to screen a cDNA library constructed from RNA fractions enriched in the various transferase mRNAs. Two clones which have been identified, pGTB38 and pGTA/C36, are complementary to the Ya/Yc mRNAs and Yb mRNAs, respectively. These clones have been utilized to determine that the Ya/Yc mRNAs and Yb mRNA(s) are elevated coordinately in response to xenobiotic treatment; however, their maximal level of induction is markedly different. Based upon the size of the mRNA specific for the Ya/Yc and Yb subunits, as well as the lack of homology between pGTB38 and pGTA/C36, we conclude that transferase B and transferases A and C are encoded for by distinct genes.