A preliminary characterization of the cytosolic glutathione transferase proteome from Drosophila melanogaster.

The cytosolic GST (glutathione transferase) superfamily has been annotated in the Drosophila melanogaster genome database. Of 36 genes, four undergo alternative splicing to yield a total of 41 GST proteins. In the present study, we have obtained the 41 transcripts encoding proteins by RT (reverse transcription)-PCR using RNA template from Drosophila S2 cells, an embryonic cell line. This observation suggests that all of the annotated DmGSTs (D. melanogaster GSTs) in the proteome are expressed in the late embryonic stages of D. melanogaster. To avoid confusion in naming these numerous DmGSTs, we have designated them following the universal GST nomenclature as well as previous designations that fit within this classification. Furthermore, in the cell line, we identified an apparent processed pseudogene, gste8, in addition to two isoforms from the Delta class that have been published previously. Only approximately one-third of the expressed DmGSTs could be purified by conventional GSH affinity chromatography. The diverse kinetic properties as well as physiological substrate specificity of the DmGSTs are such that each individual enzyme displayed a unique character even compared with members from the same class.