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. Author manuscript; available in PMC: 2015 Nov 5.
Published in final edited form as: Expert Rev Mol Med. 2010 Feb 1;12:e5. doi: 10.1017/S1462399409001367

Figure 1. Composition of heparan sulfate disaccharide units.

Figure 1

Heparan sulfate is composed of repeating disaccharide units of hexuronic acid (either glucuronic or iduronic acid) alternating with an N-substituted (R′ = acetate or sulfate) or unsubstituted (R′ = H) glucosamine. Both N-acetylated and N-sulfated glucosamine are commonly found in mature HS chains, whereas N-unsubstituted glucosamine is not. Glucosamine can also be sulfated at the C-6 and C-3 position, although 3-O-sulfated glucosamine is rare in HS. The hexuronic acids can be sulfated at the C-2 position, and this is a common modification in iduronic acid (2-O-sulfated iduronic acid). In general, the unique sulfation pattern dictates the ligand-binding specificity of HS.