title: The oligosaccharide units of rabbit immunoglobulin G. Multiple carbohydrate attachment sites.
abstract: The carbohydrate structure of rabbit immunoglobulin G isolated from pooled sera was investigated. Amino sugar analysis of fragments of the molecule allowed three oligosaccharides to be located at separate sites on the H-chain. The corresponding glycopeptides were isolated. The average composition of the C1-oligosaccharide was 2 glucosamine, 1 mannose and 2 galactose residues. It appeared to be present in approx. 15% of the H-chains; the carbohydrate was coupled through the amide group of asparagine in a peptide containing asparagine, glycine and threonine within the Fd fragment of the molecule. The average composition of the C2-oligosaccharide was 1 galactosamine, 1 galactose and either 1 or 2 sialic acid residues. It was present on approx. 40% of the H-chains and was attached glycosidically to the OH group of threonine in a peptide Ser-Lys-Pro-Thr-Cys-Pro-Pro-Glu-Leu in the hinge region of the molecule. The average composition of the C3-oligosaccharide was 5 glucosamine, 2 galactose, 5 mannose, 1 fucose and 1 sialic acid residue. It appeared to be present in all the H-chains and was linked through the amide group of asparagine in a peptide Gln-Gln-Phe-Asn-Ser-Thr-Ile-Arg within the Fc fragment of the molecule.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001216:Asparagine / Q000032:analysis; D001665:Binding Sites; D002845:Chromatography; D002850:Chromatography, Gel; D005643:Fucose / Q000032:analysis; D005688:Galactosamine / Q000032:analysis; D005690:Galactose / Q000032:analysis; D005944:Glucosamine / Q000032:analysis; D005998:Glycine / Q000032:analysis; D006020:Glycopeptides / Q000032:analysis; D007128:Immunoglobulin Fragments / Q000032:analysis*; D007074:Immunoglobulin G / Q000032:analysis*; D008358:Mannose / Q000032:analysis; D009438:Neuraminic Acids / Q000032:analysis; D009844:Oligosaccharides / Q000032:analysis*; D010455:Peptides / Q000032:analysis; D011817:Rabbits / Q000276:immunology; D013912:Threonine / Q000032:analysis
chemical_list: D006020:Glycopeptides; D007128:Immunoglobulin Fragments; D007074:Immunoglobulin G; D009438:Neuraminic Acids; D009844:Oligosaccharides; D010455:Peptides; D005643:Fucose; D013912:Threonine; D001216:Asparagine; D005688:Galactosamine; D005944:Glucosamine; D008358:Mannose; D005998:Glycine; D005690:Galactose