FIGURE 1. Scheme of HS chain biosynthesis.
From the following article:
Specificities of heparan sulphate proteoglycans in developmental processes
Norbert Perrimon and Merton Bernfield
Nature 404, 725-728(13 April 2000)
doi:10.1038/35008000
The chains are synthesized on the core protein by the sequential action of individual glycosyltransferases. A common tetrasaccharide linkage region is formed, followed by the addition of alternating GlcA and GlcNAc residues, producing in turn the precursor chain. This chain is then enzymatically modified by deacetylation and N-sulphation, epimerization and O-sulphation, yielding individual chains whose sequence is distinct from all other chains.
