Structural characterization of murine ia antigen n-linked oligosaccharides and localization of specific structures to two unique α-chain glycosylation sites
1985; Elsevier BV; Volume: 22; Issue: 2 Linguagem: Inglês
10.1016/s0161-5890(85)80007-9
ISSN1872-9142
AutoresElliot P. Cowan, Richard D. Cummings, David R. Lee, Benjamin D. Schwartz, Susan E. Cullen,
Tópico(s)Carbohydrate Chemistry and Synthesis
ResumoThe sequence of N-linked oligosaccharides of differentially glycosylated murine I-Ak α- (α2- and α3-) and β-chains was determined. I-Ak β-chains predominantly bear a biantennary complex oligosaccharide with a core fucose, and with the peripheral sequence SA→Gal→GlcNAc→Man. The I-Ak α-chain has two N-linked glycosylation sites at Asn-82 and Asn-122. When Lubrol-insoluble α3-chains are examined they are found to bear high-mannose oligosaccharides of either the Man9GlcNAc2 or Man8GlcNAc2 type at both sites. When Lubrol-soluble α2-chains are examined, in about 85% of the molecules the Asn-82 site bears a biantennary complex oligosaccharide with core fucose, and with the peripheral sequence SA→Gal→GlcNAc→Man. Interestingly, the Asn-122 site bears a variety of structures. In about 50% of the molecules, the structure at Asn-122 is a biantennary complex oligosaccharide without core fucose and with the peripheral sequence SA→Gal→GlcNAc→Man. In addition, it can bear other complex structures which we did not define further. The apparently restricted addition of fucose to the oligosaccharide at the α-Asn-82 site, even when both α-sites bear biantennary complex structures with the same peripheral sequence, is a feature unique to this system. The unusual variety of structures present at the α-Asn-122 site may indicate differential processing in different cell types.
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