Human testicular glutathione S-transferases: insights into tissue-specific expression of the diverse subunit classes.

Cytosolic glutathione S-transferase (GST) subunits from human testis were resolved by HPLC and unambiguously identified by combined use of peptide sequence-specific antisera and electrospray ionization mass spectrometry (ESI MS). Allelic variants of hGSTP1, hGSTM1 and hGSTA2 were distinguished on the basis of observed differences in their molecular masses. Relative amounts of the multiple different subunit types in various human tissues were determined from HPLC profiles. From this type of analysis, tissues from hGSTM1 null allele individuals were readily discerned at the protein level; liver was the only tissue in which the hGSTM1 subunit was the major mu-class GST. hGSTM4 and hGSTM5 subunits were found at very low levels in all tissues examined. By far the tissue richest in the unique hGSTM3 subunit was testis, although brain also has significant levels.