Identification of increased amounts of UDP-glucuronyltransferase protein in phenobarbital-treated chick-embryo liver cells

Abstract

UDP-glucuronyltransferase activity of neonatal-chick liver or phenobarbital-treated chick-embryo liver catalyzed the glucuronidation of 1-naphthol, 4-nitrophenol and 2-aminophenol. Only low transferase activity towards testosterone was detected, and activity towards bilirubin was not detectable. Liver microsomal transferase activity towards the 3 phenols was increased .apprx. 20- to 50-fold by phenobarbital treatment of chick embryos or by transfer of liver cells into tissue culture. A single form of UDP-glucuronyltransferase, which appears to catalyze the glucuronidation of these 3 phenols, was purified to near homogeneity from phenobarbital-treated chick-embryo liver microsomal fraction for the 1st time. The use of this purified enzyme as a standard protein facilitated the identification of this protein in chick-embryo liver microsomal fraction. The accumulation of this microsomal protein was observed following phenobarbital treatment of chick embryos and during tissue culture of chick-embryo liver cells. The value of this model system for the study of the induction of UDP-glucuronyltransferase by drugs and hormones is discussed.