Elongation of N ‐Acetyllactosamine Repeats in Diantennary Oligosaccharides

Glycosylated [Asn22]lysozyme has been shown to contain N ‐acetyllactosamine repeats when expressed in Chinese hamster ovary (CHO) cells. We find that the major portion of N ‐acetyllactosamine repeats are associated with diantennary oligosaccharides. In Lec2 CHO cells, which are deficient in sialylation, glycosylated lysozyme is synthesized with increased contents of N ‐acetyllactosamine repeats terminating in β‐galactosyl 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 β‐ N ‐acetylglucosaminyl transferase and by the synthesis of β‐1,6‐linked antennae. The results with glycosylated lysozyme suggest that glycoproteins bearing diantennary oligosaccharides can contain several N ‐acetyllactosamine repeats and that the number of the latter can be increased by decreasing the activity of the capping sialyl transferases.