Glycosyltransferase activities of highly purified fractions of Golgi apparatus, plasma membrane and endoplasmic reticulum, all from the same homogenates, were analyzed and compared. Additionally, Golgi apparatus were unstacked and the individual cisternae separated into fractions enriched in cis, median and trans elements using the technique of preparative free-flow electrophoresis. Golgi apparatus from both liver and
hepatomas were enriched in all
glycosyltransferases compared to endoplasmic reticulum and plasma membranes. However, Golgi apparatus from
hepatomas showed both elevated
fucosyltransferase and
galactosyltransferase activities but reduced
sialyltransferase and
dipeptidyl peptidase IV (DPP IV) activities compared to liver. Activity of
N-acetylglucosaminyltransferase was approximately the same in both liver and
hepatoma Golgi apparatus. With normal liver, sialyl- and
galactosyltransferase activities and DPP IV showed a marked cis-to-trans gradient of activity.
Fucosyltransferase was concentrated in two regions of the electrophoretic separations, one corresponding to cis cisternae and one corresponding to trans cisternae.
N-Acetylglucosaminyltransferase activity was more widely distributed but the endogenous acceptor activity was predominantly cis. With
hepatoma Golgi apparatus, the pattern for DPP IV was similar to that for liver but those of sialyl- and
galactosyltransferases differed markedly from liver. Instead of activity increasing cis to trans, the activities for sialyl- and
galactosyltransferases decreased. For
fucosyltransferases, activity dependent on exogenous acceptor was medial whereas with endogenous acceptor, two activity peaks, cis and trans, still were observed. For
N-acetylglucosaminyltransferase the pattern for
hepatoma was similar to that for liver. The results indicate alterations in the distribution of
glycosyltransferase activities within the Golgi apparatus in hepatotumorigenesis that may reflect altered cell surface glycosylation patterns.