PathwayStep1056 PathwayStep1068 PathwayStep1059 PathwayStep1057 PathwayStep1058 PathwayStep1063 PathwayStep1062 PathwayStep1061 PathwayStep1060 PathwayStep1067 PathwayStep1066 PathwayStep1065 PathwayStep1064 HS-GAG biosynthesis Authored: Jassal, B, 2011-12-01 Edited: Jassal, B, 2011-12-01 GENE ONTOLOGYGO:0006024 Heparan sulfate (HS) and heparin (sometimes collectively called HS-GAG) consist of the disaccharide unit GlcNAc-GlcA (N-acetylglucosamine-glucuronic acid) connected by a beta1,4 linkage. Heparin is exclusively made in mast cells whereas HS is made by virtually every type of cell in the body. As the chain length increases, the polysaccharides can undergo modifcations such as epimerisation of glucuronic acid to iduronic acid and deacetylation and sulfation of GlcNAc to form sulfated glucosamine (Stringer & Gallagher 1997, Sasisekharan & Venkataraman 2000). Pubmed11102866 Pubmed9251237 Reactome Database ID Release 432022928 Reactome, http://www.reactome.org ReactomeREACT_121248 Reviewed: D'Eustachio, P, 2012-03-28 HS3ST1 sulfates GlcN at C3 in heparan sulfate GLCE epimerises more GlcA to IdoA as sulfate content rises HS3STs sulfate GlcN at C3 in heparan sulfate HS6STs sulfate GlcN at C6 in heparan sulfate/heparin Some HSPGs are secreted to the plasma membrane The addition of GlcNAc to the terminal glucuronate residue creates heparan Glucuronate is added to the heparan chain Another GlcNAc addition extends the heparan chain Another GlcA addition extends the heparan chain NDST1-4 N-deacetylates GlcNAc residues in heparan NDST1-4 can sulfate a glucosamine residue in heparan to form heparan sulfate (HS) GLCE epimerises GlcA to IdoA HS2ST1 sulfates IdoA at C2 in heparan sulfate