N-Acetylglucosaminyltransferase Activity in Liver, Serum, and Ovaries of Domestic Fowl

Abstract

Homogenates of the liver, serum, and ovaries of the laying hen and the liver and serum of the immature pullet were examined for N-acetylglucosaminyltransferase activity. The activity in the liver homogenates was higher in the laying hen than in the pullet while their sera showed similar low levels of enzyme activity. The homogenate of the ovary from the laying hen was also found to contain N-acetylglucos-aminyltransferase. Golgi-rich and Golgi-depleted membrane fractions were prepared from the liver homogenates of both types of fowl and examined in the assay system. The Golgi-depleted membrane fractions from the livers of both laying hen and pullet had higher enzyme activities than the corresponding Golgi-rich fractions. The N-acetylglucosaminyltransferase activities in both cellular membrane fractions were higher in the laying hen than in the pullet. The results are compatible with the hypothesis that N-acetylglucosaminyltransferase is involved in synthesis of lipoproteins and/or glycoproteins by the liver and the ovary. In contrast to the rat, the hen enzyme did not show increased activity in the presence of added CDP-choline.