ISOLATION AND ANALYSIS OF THE GENE AND CDNA FOR A HUMAN MU CLASS GLUTATHIONE-S-TRANSFERASE, GSTM4

We have isolated the human gene and cDNA that encode the fourth member of the Mu class glutathione S-transferases (GSTs). The complete gene sequence (GenBank M96233) and the cDNA sequence (M96234) are reported and named GSTM4. The gene, located on chromosome 1, is comprised of ei ght exons with an organization similar to that of other Mu class genes . GSTM4 differs from a partial gene sequence, termed GSTmu2 (Taylor, J . B., Oliver, J., Sherrington, R., and Pemble, S. E. (1991) Biochem. J . 274, 587-593), in exons 3 through 5 by only 11 nucleotides within in trons. The cDNA for GSTM4 was isolated from a library derived from the cervical carcinoma cell line, HeLa. Northern blots demonstrate the pr esence of GSTM4 mRNA in human heart, placenta, lung, brain, liver, ske letal muscle, pancreas, testis, cerebral cortex, uterus, ovary, a lymp hoblastoid cell line, and four carcinoma cell lines. The deduced amino acid sequence of GSTM4 is 87% (GSTM1), 83% (GSTM2), and 70% (GSTM3) i dentical to the previously described human Mu class GSTs. The polypept ide encoded by the GSTM4 cDNA, produced in a bacterial expression syst em, conjugates 1-chloro-2,4-dinitrobenzene to GSH with a specific acti vity of 1.39 +/- 0.21 mumol/min/mg.