Glycan arrays for functional glycomics

Abstract

Interactions between carbohydrates and proteins mediate intracellular traffic, cell adhesion, cell recognition and immune system function. Two recent papers describe how arrays of oligosaccharide and polysaccharide molecules can be used to investigate these interactions more fully.

Figure 1

Two conceptual approaches to screening glycan libraries. (a) When specific target cell types or glycoprotein ligands are known for a lectin, oligosaccharides released specifically from these sources can be separated by chromatography and examined by probing a relatively small array. (b) In the alternative 'glycomic' approach, a generic library of purified glycans produced synthetically and/or from natural sources can be screened with various different lectins.

Figure 2

Possible outcomes of screening glycan libraries. (a) Some lectins, such as the selectin cell-adhesion molecules, will recognize a few specific endogenous mammalian glycans with related structures, such as the sialyl-Lewis glycans shown. (b) Other lectins, such as the macrophage mannose receptor, will bind broader classes of endogenous and microbial glycans, such as those shown below the array; the receptor is shown recognizing structures that bear terminal mannose or N-acetylglucosamine residues.