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 3Gal 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.
Highlights
50%of these molecules have the structure GalB1+3GalNAc which is identical with the structure of the predominant oligosaccharide in the hinge region of human IgA, myelomaproteins
The complete amino acid sequence of 1gD:WAH has been reported and the locationosf the four orfive oligosaccharides 0-glycosidically linked via GalNAc to hinge region Ser/Thr residues determined [14]
Theresults indicated that Gal and GalNAcwere present in nearly equimolar amounts and that sialic acid was present at approximately 50% of thisamount.Asthestructure of the predominant 0-glycosidically linked oligosaccharide present in the hingeregion of human IgA has been determined to be Galpl-t3GalNAc (I), thecompositionaldata we obtained suggested that the same structumraey be present in the hinge region of 1gD:WAH with the additional presencoef sialylated derivatives
Summary
In. 11556), the structuresof the oligosaccharides present of 0-glycosidically linked carbohydrate among all the immuat the 3 asparagineglycosylation sites of a human IgD noglobulin classes of humans [8].The hinge region is believed myeloma proteinwere defined. 11556), the structuresof the oligosaccharides present of 0-glycosidically linked carbohydrate among all the immuat the 3 asparagineglycosylation sites of a human IgD noglobulin classes of humans [8].The hinge region is believed myeloma proteinwere defined In this communication, we present the structureosf the 0-glycosidically linked oligosaccharideloscated in thheingreegioonf 1gD:WAH. We present the detailed structural characterization of the 0-glycosidically (NeuAca2+6)GalNAc (12%),and NeuAca2+3Gal/31+ linked oligosaccharides of IgD as well as information regard-. 3(NeuAca2+6)GalNAc (8%).The sialylated molecules ing the distribution of different oligosaccharide structures have not been encountered previouslyon other human within the hinge region. Thesestructures, have been described on a number of secreted and EXPERIMENTAL PROCEDURES
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