Characterization of N-linked oligosaccharides of an HLA-DR molecule expressed in different cell lines.

In order to determine the factors that influence the glycosylation of an integral membrane protein, we investigated the N-glycosylation of a molecule of the human major histocompatibility complex (MHC) class II, the HLA-DR antigen. This glycoprotein was studied in a human Epstein-Barr-virus-transformed B cell line and in a mouse fibroblastic cell line co-transfected with DR alpha and DR beta genes. We observed that the HLA-DR-antigen glycosylation pattern depends on the cell line in which processing takes place and is closely related to the glycosylation pattern of the overall cellular glycoproteins. Furthermore, when comparing the glycosylation of the separated alpha- and beta-chains, differences were noticed within the same molecule, showing the importance of the individual peptide backbone for the glycosylation process.