Carbohydrate recognition in the immune system: contributions of neoglycolipid-based microarrays to carbohydrate ligand discovery.
Bottom Line: The pinpointing and characterizing of oligosaccharide ligands within glycomes has been one of the most challenging aspects of molecular cell biology, as oligosaccharides cannot be cloned and are generally available in limited amounts.This overview recounts the background to the development of a microarray system that is poised for surveying proteomes for carbohydrate-binding activities and glycomes for assigning the oligosaccharide ligands.Particularly highlighted are sulfo-oligosaccharide and gluco-oligosaccharide recognition systems elucidated using microarrays.
Affiliation: The Glycosciences Laboratory, Department of Medicine, Imperial College London, London, United Kingdom. firstname.lastname@example.orgShow MeSH
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Mentions: In the case of siglec recognition, however, microarray analyses have shown that the interchangeable role for sulfate and the sialic acid carboxyl group does not apply. As their name implies, siglecs absolutely require terminal sialic acid for binding (Fig. 4). Sulfate on sialyl oligosaccharide sequences can, nevertheless, modulate the strength of siglec binding.51 For example, the presence of sulfate 6-linked to the adjoining galactose or 6-linked to the inner monosaccharide, N-acetylglucosamine, can variously enhance or suppress interactions of the sialyl ligands of siglecs (Figs. 4 and 5). A detailed review of the modulatory effects of sulfation on oligosaccharide ligand recognition is out of the scope of this article. Suffice it to highlight that with well characterized, chemically synthesized glycolipids it was shown that with L-selectin, 6-linked sulfate at subterminal N-acetyl glucosamine (popularly termed 6-sulfo-sialyl-sialyl-Lex), enhances the binding to the sialyl-Lex sequence and creates the preferred ligand for this selectin.66 This was corroborated by subsequent studies.67 In contrast, 6-linked sulfate at the galactose, 6′-sulfo-sialyl-sialyl-Lex, suppresses L-selectin binding while creating the preferred ligand for langerin.49,66
Affiliation: The Glycosciences Laboratory, Department of Medicine, Imperial College London, London, United Kingdom. email@example.com