Analysis of the oligosaccharides on the HLA-DR and DC1 B cell antigens.

The types of N-linked oligosaccharides on the HLA-DR and DC1 antigens were determined by their sensitivity to endoglycosidase H or endoglycosidase D. The DR and DC1 heavy chains each have two carbohydrate moieties, one high-mannose and one complex-type glycan. The DR and DC1 light chains have one complex-type oligosaccharide. During the biosynthesis of the DR antigens, the oligosaccharides on both subunits are initially high-mannose-type glycans, as has been found for other membrane glycoproteins. The light chain oligosaccharide and one of the two heavy chain carbohydrates are later processed to complex-type glycans. Inhibition of N-linked glycosylation with tunicamycin does not inhibit chain association of the DR and DC1 subunits, transport to the cell surface, or expression of the alloantigenic determinants.