Expression of human glutathione S-transferase 2 in Escherichia coli. Immunological comparison with the basic glutathione S-transferases isoenzymes from human liver.

A plasmid, termed pTacGST2, which contains the complete coding sequence of a GST2 (glutathione S-transferase 2) subunit and permits the expression of the protein in Escherichia coli was constructed. The expressed protein had the same subunit Mr as the enzyme from normal human liver and retained its catalytic function with both GST and glutathione peroxidase activity. Antiserum raised against the bacterially synthesized protein cross-reacted with all the basic GST isoenzymes in human liver. The electrophoretic mobility in agarose of the bacterially expressed isoenzyme suggested that its pI is identical with that of the cationic isoenzyme from human liver previously termed GST2 type 1. The available evidence suggests that the three common cationic isoenzymes found in human liver are the products of two very similar gene loci.