The role of protein glycosylation in the control of cellular N-sialyltransferase activity

Protein glycosylation, which is a key post-translational event, is catalysed by the glycosyltransferase family of enzymes. There is an increasing body of evidence to suggest that these enzymes may themselves be glycosylated, possibly as an autocatalytic event. Using a novel in vitro system, we have investigated the role of enzyme glycosylation in sialyltransferase catalytic activity. The enzyme activity is glycosylation dependent, with the penultimate galactose residue on complex N-linked oligosaccharides playing a pivotal role. These results serve to underline the complexity of the glycosylation process.