Identification of a characteristic cytosolic polypeptide of rat preneoplastic hepatocyte nodules as placental glutathione S-transferase.

Evidence is presented that a distinctive type of glutathione-S-transferase (GSHTase-P), and a cytosolic polypeptide of Mr 52,000 (P-52), each appearing in greatly increased amounts in hepatocyte nodules during liver carcinogenesis in the rat, are so far indistinguishable. The probable identity of the two polypeptides was established with the use of SDS polyacrylamide gel electrophoresis and Western blot techniques with purified GSHTase-P and P-52 and their respective antibodies and by comparison of the sequence of the first 26 N-terminal amino acids. Since the enzyme and the polypeptide are each considered to be the best available early markers for hepatocyte nodules, as putative precancerous lesions, their probable identity makes them attractive cellular components for in depth studies on their transcriptional and translational regulation and their use in new approaches to the sequential analysis of liver carcinogenesis.