Incorporation of radioactive glucosamine into submicrosomal fractions isolated from rat liver

The incorporation of [1-¹⁴C[glucosamine into various submicrosomal fractions and cell sap from rat liver, as well as into plasmaproteins, has been examined after intraperitoneal injection. It has been shown that after 1 h there is a significant incorporation of protein-bound radioactivity into the submicrosomal fractions. 69% of the total radioactivity was found in the ultrasonic extract of the microsomal pellet, 28% in the subsequent deoxycholate extract and 3% associated with the ribosomes. Of the total radioactivity in the ultrasonic extract and the deoxycholate extract, more than 80% was found in the perchloric acid precipitate and only about 5–10% in the phosphotungstic acid precipitate. 15% of the protein-bound radioactivity in the perchloric acid precipitate of the ultrasonic extract was associated with a sialic acid fraction and about 1% found in the hexose fraction. Most of the remaining radioactivity was associated with glucosamine. The intracellular site for the biosynthesis of glycoproteins is discussed.