Title :
Oligosaccharide microheterogeneity of the murine major histocompatibility antigens
Abstract :
- Reproducible site-specific patterns of sialylation and branching in asparagine-linked oligosaccharides. asparagine-linked oligosaccharides
- The influence of peptide structure of endogenous cell-surface glycoproteins on the branching and sialylation of their asparagine-linked oligosaccharides asparagine-linked oligosaccharides was evaluated in a murine B cell lymphoma, AKTB-1b
- This cell line simultaneously synthesizes two classes of major histocompatibility antigens that, within each class, share a high degree of amino acid sequence homology and possess potential N-linked glycosylation sites at invariant positions
- [3H]Mannose-labeled oligosaccharides were released from each of 11 purified glycosylation sites by the almond peptide : N-glycosidase and analyzed by a variety of chromatographic procedures and glycosidase treatments
- The data indicate: 1) a unique distribution of oligosaccharide structures is present at each glycosylation site ; 2) each site-specific oligosaccharide pattern is highly reproducible, independent of the number of in vivo tumor passages
- The heavy chain of the class I antigens, H-2Kk and H-2Dk contain two and three sites , respectively, in which biantennary structures predominate
- However, each site varies with respect to the extent of sialylation and the proportions of more highly branched structures present
- The class II antigens, I-Ak and I-Ek, each contain an alpha-chain site toward the N terminus and a single beta-chain site where the overall extent of sialylation is similar, yet the distributions of antennary structures are dramatically different for each
- The alpha-chains of each class II antigen also contain a more C-terminal underglycosylated site where sialylation and branching are reduced to differing degrees depending upon the site
- The influence of peptide structure on oligosaccharide microheterogeneity is manifest at two levels
- First, the overall distributions of oligosaccharides at corresponding sites on structurally related glycoproteins are similar
- Second, the specific "fingerprint" of sialylation and branching patterns at a particular site are reproducibly unique
- These data suggest that subtle changes in peptide structure are reflected in the extent of sialylation and branching of oligosaccharides found at corresponding glycosylation sites of structurally related glycoproteins