Characterization of MOPC 315 IgA oligosaccharide processing intermediates.

The structures of alpha 1,2-mannose containing partially processed asparagine-linked oligosaccharides on the alpha-chain of MOPC 315 IgA were characterized using specific glycosidases and acetolysis. Man6GlcNAc2, a substrate for a Golgi alpha 1,2-mannosidase, was found to be a single isomeric structure. Likewise, Man7-9GlcNAc2 were single isomers indicating an ordered sequence of removal of alpha 1,2-linked mannose residues on this murine immunoglobulin heavy chain.