Chondroitin sulfate proteoglycans, which consist of a core protein with at least 1 covalently attached glycosaminoglycan (GAG) chain, are distributed on the surfaces of most cells and the extracellular matrix in virtually every tissue.Chondroitin 6-sulfotransferase (C6ST) catalyzes the transfer of sulfate from PAPS (3-prime-phosphoadenosine 5-prime-phosphosulfate) to position 6 of the GalNAc residues.

The predicted 479-amino acid protein shares 74% and 36% identity with chick C6ST and human keratan sulfate gal-6-sulfotransferase (CHST1), respectively. Recombinant human enzyme displayed C6ST activity with a marked specificity for a GlcA-GalNAc sequence. In addition, C6ST catalyzed the sulfation of keratan sulfate.