Abstract
Sulfotransferases so far cloned which are involved in the synthesis of chondroitin sulfate are classified into three gene families: chondroitin 6-sulfotransferase (C6ST) family, chondroitin 4-sulfotransferase (C4ST) family and uronosyl 2-O-sulfotransferase (UA2OST) family. The C6ST family includes sulfotransferases which catalyze the transfer of sulfate to position 6 of Gal residue of keratan sulfate and sialyllactosamine oligosaccharide, and to position 6 of nonreducing terminal GlcNAc residue. In the C4ST family, sulfotransferases which catalyze the transfer of sulfate to position 4 of nonreducing terminal GalNAc residue and to position 3 of nonreducing terminal GlcA residue are present. UA2OST was cloned as a cDNA showing homology with heparan sulfate 2-sulfotransferase that transfers sulfate to position 2 of Ido A residue in heparan sulfate. It became evident that, in some cases, sulfotransferases involved in the sulfation of glycosaminoglycans and sulfotransferases involved in the sulfation of oligosaccharides of glycoproteins are included in a common gene family. A sulfotransferase with a novel specificity may be found in these families, or a new sulfotransferase other than known families may be revealed in the future. Findings of a new sulfotransferase will offer important information about the biological function of sulfated sugar chains.
