Genomic organization, 5'-flanking region and chromosomal localization of the human glutathione transferase A4 gene.

We have isolated and characterized a human glutathione transferase A4 (hGSTA4) subunit gene from a yeast artificial chromosome containing several other glutathione transferase alpha genes and pseudogenes. The homodimeric protein hGSTA4-4, is involved in the detoxification of 4-hydroxynonenal and other reactive electrophiles produced by oxidative metabolism, and may have a significant role in protecting intracellular components from oxidative damage. The hGSTA4 gene spans nearly 18 kb, contains seven exons, maps onto chromosome 6p12, and lies in close proximity to the 7SK small nuclear RNA gene in a head-to-tail orientation. The intron/exon borders conform to the standard rules, an open reading frame is present beginning at position 154 in exon 2, and the stop codon is at position 822 in exon 7. The transcription initiation site has been determined by primer extension analysis and is located 135 bp upstream of intron 1. Isolation and sequencing of the hGSTA4 gene 5'-flanking region revealed it to be devoid of TATA or CCAAT boxes but it does contain an initiator element overlapping the transcription start site, a GC box and putative binding sites for transcription factors AP1, STAT, GATA1 and NF-kappaB. Reverse transcription-PCR analysis revealed that hGSTA4 mRNA was present in all the tissues tested, although in low amounts, suggesting that this subunit may be ubiquitously expressed.