Comparative studies on the uridine-5'-diphosphate-galactose: glycoprotein galactosyltransferase activity in rat liver and Zajdela ascitic hepatoma.

We report here data on the galactosyltransferase activity in serum, liver and Zajdela ascitic hempatoma cells and about the rate of galactose attachment to appropriate acceptors by beta(1-4, beta(1-3) and alpha(1-3) linkages in liver and hepatoma cell homogenates. It was established that in serum of Zajdela bearing rats, in host liver and in Zajdela ascitic cells, galactosyltransferase activity towards ovomucoid was elevated in comparison with control serum and liver. The activity towards low molecular acceptor (N-acetylglucosamine) in liver and hepatoma was nearly the same. The predominant isomer synthesized in both tissues was beta 1-4-galactose-N-acetylglucosamine. When asialofetuin was used as acceptor the activity of alpha(1-3) galactosyltransferase was measured. In Zajdela ascitic hepatoma cells alpha(1-3) galactosyltransferase activity was 3 times higher than that in liver. The elevated ability of the tumor cells to attach galactose residues with alpha(1-3) linkage to Gal beta 1-4GlcNAc-R sequence should be considered as a characteristic feature of these malignant cells.