This gene encodes the enzyme heparan sulfate D-glucosaminyl 3-O-sulfotransferase 4. This enzyme generates 3-O-sulfated glucosaminyl residues in heparan sulfate. Cell surface heparan sulfate is used as a receptor by herpes simplex virus type 1 (HSV-1), and expression of this gene is thought to play a role in HSV-1 pathogenesis. [provided by RefSeq, Jul 2008].