ELONGATION OF N-ACETYLLACTOSAMINE REPEATS IN DIANTENNARY OLIGOSACCHARIDES

Glycosylated [Asn22]lysozyme has been shown to contain N-acetyllactosa mine repeats when expressed in chinese hamster ovary (CHO) cells. We f ind that the major portion of N-acetyllactosamine repeats are associat ed with diantennary oligosaccharides. In Led CHO cells, which are defi cient in sialylation, glycosylated lysozyme is synthesized with increa sed contents of N-acetyllactosamine repeats terminating in beta-galact osyl residues. In the Lec2 cells and the parental CHO cell line, Pro-5 , only a minor portion of the oligosaccharides in lysozyme are of the triantennary type. previously it has been shown that the synthesis of N-acetyllactosamine repeats in Asn-linked oligosaccharides is enhanced by an increase in the activity of the elongating beta-N-acetylglucosa minyl transferase and by the synthesis of beta-1,6-linked antennae. Th e results with glycosylated lysozyme suggest that glycoproteins bearin g diantennary oligosaccharides can contain several N-acetyllactosamine repeats and that the number of the latter can be increased by decreas ing the activity of the capping sialyl transferases.