Title : Structures of the O-glycosidically linked oligosaccharides of human IgD
Abstract :
In the previous communication (Mellis, S. J., and Baenziger, J. U. (1983) J. Biol
Chem
258, 11546-11556), the structures of the oligosaccharides present at the 3 asparagine glycosylation sites of a human IgD myeloma protein were defined
In this communication, we present the structures of the O-glycosidically linked oligosaccharides located in the hinge region of IgD :WAH
Three or four threonine residues and one serine residue in the region bear O-glycosidically linked oligosaccharides
Approximately 50% of these molecules have the structure Gal beta 1 leads to 3 GalNAc which is identical with the structure of the predominant oligosaccharide in the hinge region of human IgA1 myeloma proteins (Baenziger, J. U., and Kornfeld, S. (1974) J. Biol
Chem
249, 7270-7281)
The remainder of the oligosaccharides contain 1 or 2 residues of N-acetylneuraminic acid and have the structures NeuAc alpha 2 leads to 3 Gal beta 1 leads to 3GalNAc (30%), Gal beta 1 leads to (NeuAc alpha 2 leads to 6)GalNAc (12%), and NeuAc alpha 2 leads to 3Gal beta 1 leads to 3(NeuAc alpha 2 leads to 6)GalNAc (8%)
The sialylated molecules have not been encountered previously on other human immunoglobulin heavy chains
These structures, however, have been described on a number of secreted and membrane glycoproteins
Examination of oligosaccharides isolated from different subregions of the IgD hinge indicated that a specific distribution of the sialylated structures among the glycosylated amino acids of the hinge region is not likely