Figure 1

Glycan structures of the six classes of secretory glycan (N-glycans, hyaluronan, O-glycans, glycolipids, glycosylphosphatidylinositol (GPI) anchor and glycosaminoglycans) and the single intracellular glycan O-linked β-N-acetylglucosamine (O-GlcNAc) are shown. Representative examples of each type are indicated using the symbol nomenclature for monosaccharides (see key). Multiple and multi-antennary examples of the predominant mature, complex-type N-glycans are shown, including the high-mannose N-glycan that is found attached to some glycoproteins. Examples of core 1–4 O-glycans are depicted, as well as O-mannose, O-fucose and O-glucose structures. Core 5–7 O-glycans are not shown. The GPI anchor and examples of the glycosaminoglycans and glycolipids are also depicted. In all examples, glycan linkages are identified by the anomeric configuration (α orβ) of the donor saccharide following its linkage to the ring position (1–6) of the glycan acceptor. Et–P denotes a phosphoethanolamine linkage. NS, 2S, 4S and 6S denote the sulphation positions of the glycosaminoglycan chains. Asn, asparagine; Ser, serine; Thr, threonine.