Description
Heparan sulfate is a highly sulfated polysaccharide found on the cell surface and within the extracellular matrix. Typically, it is covalently attached to the protein core of proteoglycans, such as syndecans and glypicans. Heparin, on the other hand, can be considered as a highly sulfated version of heparan sulfate that is predominantly found in mast cells. Both heparin and heparan sulfate contain disaccharide repeats of uronic acid and Nacetylglucosamine and are modified by the same sulfotransferases (1, 2). The uronic acid residues are either glucuronic acid or iduronic acid and maybe sulfated at the 2O position by heparan sulfate 2O sulfotransferase 1 (HS2ST1) (3, 4). HS2ST1 physically interacts in the Golgi apparatus with glucuronyl c5epimerase (5), which catalyzes the conversion of glucuronic acid to iduronic acid (6). As a consequence, 2O