HGSNAT acetylates the terminal N-glucosamine in heparan sulfate Authored: Jassal, B, 2011-10-19 EC Number: 2.3.1.78 Edited: Jassal, B, 2011-10-19 Heparan-alpha-glucosaminide N-acetyltransferase (HGSNAT) acetylates the non-reducing terminal alpha-glucosamine residue of heparan sulfate. This is a critical reaction for the degradation of heparan sulfate because there is no enzyme that can act on the unacetylated glucosamine molecule. The mechanism by which HGSNAT uses cytosolic acetyl-CoA to transfer the acetyl group to the lysosomal luminal substrate is unknown (Fan et al. 2006). A catalytically inactive 77kDa precursor is transported to the lysosome and is cleaved into a 29kDa N-terminal alpha-chain and a 48kDa C-terminal beta-chain, which are assembled into active 440kDa oligomers in the lysosomal membrane (Durand et al. 2010). Defects in HGSNAT cause mucopolysaccharidosis type IIIC (MPSIIIC, MIM:252930), also called Sanfilippo C syndrome (Fan et al. 2006, Hrebicek et al. 2006). Pubmed16960811 Pubmed17033958 Pubmed20650889 Reactome Database ID Release 431678660 Reactome, http://www.reactome.org ReactomeREACT_121010 Reviewed: D'Eustachio, P, 2012-03-28