Carbohydrate Sulfotransferase 3 (CHST3) is an enzyme that catalyzes the transfer of sulphate group from 3' phosphoadenosine 5'-phosphosulphate to position 6 of the N-acetylgalactosamine (GalNAc) residue of chondroitin. Sulphated chondroitin is the most important proteoglycan in cartilages and extracellular matrices, where it plays an important role in maintaining the structural integrity of the tissues. Apart from the GalNAc residues of chondroitin, CHST3 may also play a role in the sulphation of galactosamine residues of keratan sulphate, and sialyl N-acetyllactosamine. At least in mice, a deficiency of the enzyme has been shown to produce a decrease in the number of naïve T-lymphocytes in the spleen, indicating a role in the maintenance of these lymphocytes. In addition, more recent research has shown that the CHST3 gene is up-regulated in the central nervous system after injury, promoting migration of Schwann cells and axonal regeneration.