Figure 2.

Schematic of modifications on heparan sulphate chains by biosynthetic enzymes. HS is synthesized by sequential addition of alternating GlcA and GlcNAc by EXT1 and EXT2 respectively. Thereafter, a group of enzymes further modifies the HS chain: C5 epimerase epimerizes GlcA to IdoA, and the sulfotransferases NDST, 2‐OST, 3‐OST and 6‐OST add sulphate groups.