Heparan sulfate structures, which are responsible for executing multiple biologic activities, are generated and regulated by heparan sulfate (HS) biosynthetic enzymes. HS6ST1 (heparan sulfate 6-O-sulfotransferase 1), also known as HS6ST, is a 411 amino acid single-pass type II membrane protein that exists as multiple alternatively spliced isoforms and belongs to the sulfotransferase 6 family. Expressed in fetal brain, HS6ST1 functions as a 6-O-sulfation enzyme that specifically catalyzes the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to the N-sulfoglucosamine residue (GlcNS) HS. HS6ST1 is subject to post-translational N-glycosylation and is encoded by a functional gene on human chromosome 2 and a pseudogene on human chromosome 1 (known as LOC728969).