This gene encodes a member of the heparan sulfate/heparin GlcNAc N-deacetylase/ N-sulfotransferase family. The encoded enzyme is a type II transmembrane protein that resides in the Golgi apparatus. This monomeric bifunctional enzyme catalyzes the N-deacetylation and N-sulfation of N-acetylglucosamine residues in heparan sulfate and heparin, which are the initial chemical modifications required for the biosynthesis of the functional oligosaccharide sequences that define the specific ligand binding activities of heparan sulfate and heparin.