Rat lung glutathione S-transferases: subunit structure and the interrelationship with the liver enzymes

Six forms of glutathione S-transferases designated as GSH S-transferase I (pI 8.8), II (pI 7.2), III (pI 6.8), IV (pI 6.0), V (pI 5.3) and VI (pI 4.8) have been purified from rat lung. GSH S-transferase I (pI 8.8) is a homodimer of Mr 25,000 subunits; GSH S-transferases II (pI 7.2) and VI (pI 4.8) are homodimers of Mr 22,000 subunits; and GSH S-transferases III (pI 6.8), IV (pI 6.0) and V (pI 5.3) are dimers composed of Mr 23,500 and 22,000 subunits. Immunological properties, peptide fragmentation analysis, and substrate specificity data indicate that Mr 22,000, 23,500 and 25,000, are distinct from each other and correspond to Ya, Yb, and Yc subunits, respectively, of rat liver.