HGSNAT acetylates another terminal N-glucosamine in heparan

Stable Identifier
R-HSA-2090085
Type
Reaction
Species
Homo sapiens
Compartment
Locations in the PathwayBrowser
Summation

Heparan-alpha-glucosaminide N-acetyltransferase (HGSNAT) acetylates another 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).

Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
heparan-alpha-glucosaminide N-acetyltransferase activity of HGSNAT oligomer [lysosomal membrane]
Physical Entity
Activity
Orthologous Events