IMMUNOHISTOCHEMICAL ANALYSIS OF RAT S-ADENOSYLMETHIONINE SYNTHETASE ISOZYMES IN DEVELOPMENTAL LIVER

Mammalian S-adenosylmethionine (AdoMet) synthetase exists as two isozy mes, liver-type and kidney(non-hepatic)-type enzymes. The developmenta l expression of these two isozyme proteins has been investigated in ra t liver using immunohistochemical techniques. The liver-type AdoMet sy nthetase is expressed only in adult liver, but not in fetal liver. On the other hand, the kidney-type AdoMet synthetase is predominantly exp ressed in fetal liver and faintly detected in adult liver. It was also found that both isozymes were localized to the hepatocytes of rat liv er. These results clearly show that AdoMet synthetase isozymes are dev elopmentally regulated within hepatocytes. In addition, in rat kidney we have shown that the kidney-type AdoMet synthetase is predominantly localized to the distal tubule.