Identification of cDNAs encoding two human Alpha class glutathione transferases (GSTA3 and GSTA4) and the heterologous expression of GSTA4-4

Abstract

The Expressed Sequence Tag database has been searched for examples of previously undescribed human Alpha class glutathione transferases. An incomplete transcript of the previously described GSTA3 gene was identified in a cDNA library derived from 8-9 week placenta. This indicates that the GSTA3 gene is functional and is possibly under specific developmental regulation. A second cDNA, termed GSTA4, was identified in a brain cDNA library. The encoded GSTA4-4 enzyme was expressed in Escherichia coli and was found to be immunologically distinct from GSTA1-1 and to have high activity with alk-2-enals. Although GSTA4-4 appears to be functionally similar to the mouse GST5.7 and rat GST8-8 Alpha class enzymes, sequence comparisons and phylogenetic analysis suggest that GSTA4-4 may be a member of a distinct Alpha class subgroup.