Animal and Human Lectins - The Sugar Code - page 328

Table 19.4 Six levels of regulation of affi nity of glycan binding to a lectin.

1 Mono - and disaccharides (including anomeric position)

2 Oligosaccharides (including branching and substitutions)

3 Shape of oligosaccharide ( differential conformer selection )

4 Spatial parameters of glycans in natural glycoconjugates
(a) Shape of glycan chain (for example modulation of conformation by substitutions not
acting as lectin ligand such as core fucosylation or introduction of bisecting GlcNAc in
N - glycans, infl uence of protein part)
(b) Cluster effect with bi - to pentaantennary N - glycans or branched O - glycans [including
modulation by substitutions, please see (a)]

5 Cluster effect with different but neighboring glycan chains on the same glycoprotein (for
example in mucins)
6 Cluster effect with different glycoconjugates on the cell surface in spatial vicinity forming
microdomains

Summary Box

More than a dozen folds of animal and human proteins can accommodate a
carbohydrate ligand. Binding entails a broad range of functions. Its affi nity is
regulated by sequence changes and topological aspects on the levels of the CRD
and the glycoepitope. Respective changes on both sides can act in concert to
optimize target specifi city.

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