Congenital jaundice in rats due to the absence of hepatic bilirubin UDP-glucuronyltransferase enzyme protein.

Three major UDP-glucuronyltransferase isoenzymes (50-54 kDa) have been identified by immunoblot analysis. Bilirubin UDP-glucuronyltransferase (54 kDa) was specially induced by treatment of the rats with clofibrate. This isoenzyme was not detectable in liver microsomal extracts from congenitally jaundiced Gunn rats and was not induced by treatment of these animals with clofibrate. Phenol UDP-glucuronyltransferase, the only isoenzyme determined to be present in foetal Wistar rat liver microsomes was not detected by enzyme assay or immunoblot analysis of foetal Gunn rat liver microsomal extracts. These results provide the first indication that bilirubin UDP-glucuronyltransferase and possible phenol UDP-glucuronyltransferase proteins are not present in the congenitally jaundiced Gunn rat.