1993 Volume 5 Issue 25 Pages 355-368
Most secreted and cell surface proteins in eukaryotic cells are modified during their synthesis by the addition of oli-gosaccharides to specific Asn residues. This modification, N-linked glycosylation, can influence many aspects of the structure, function, and expression of glycoproteins (1-3). Studies using global inhibitors of N-linked glycosylation, such as tunicamycin, suggest that N-glycans may facilitate the transport of cell surface and secreted glycoproteins. However, these studies do not address whether individual N-glycans on glycoproteins play unique roles in their transport.
Recent studies have applied molecular biological methods to investigate the role of individual N-glycans in glycoprotein transport. By this approach, individual sites for N-linked glycosylation are either deleted or introduced into the cDNA encoding a given glycoprotein. The encoded protein is then expressed, and the effects of the altered pattern of glycosylation on transport are assessed. This report will review studies investigating the role of individual N-glycans in glycoprotein transport, to consider possible mechanisms by which individual N-glycans can influence glycoprotein transport, and to address special considerations in the use of site-directed mutagenesis for studies of this type.
