Oligosaccharides
The heavy chains have covalently linked oligosaccharide units and are thus glycoproteins. Each heavy chain of IgM has five such units, They contain units of mannose and N-acetyl glucosamine linked to asparagine Immunoglobulins A, E and G contain fucose, galactose and N acetylneurarninic acid in addition. The light chains lack carbohydrate.
