title: Purification and characterization of the GalNAc-4-sulfotransferase responsible for sulfation of GalNAc beta 1,4GlcNAc-bearing oligosaccharides.
abstract: The pituitary glycoprotein hormone lutropin is characterized by its pulsatile appearance in the bloodstream which is important for the expression of its biological activity in the ovary. We have previously shown that lutropin bears unique Asn-linked oligosaccharides terminating with GalNAc-4-SO4 which allow the hormone to be rapidly cleared from the bloodstream via a specific receptor in the liver, thus contributing to its pulsatile appearance in the circulation. Furthermore, we have found that carbonic anhydrase VI, synthesized by the submaxillary gland and secreted into the saliva, also bears Asn-linked oligosaccharides terminating with GalNAc-4-SO4, suggesting that this unique sulfated structure mediates other biological functions in addition to rapid clearance from the circulation. We report here the purification of a GalNAc-4-sulfotransferase which transfers sulfate to terminal beta 1,4-linked GalNAc on Asn-linked oligosaccharides. We show that the purified submaxillary gland enzyme has kinetic parameters identical to the pituitary enzyme, indicating that the same sulfotransferase is responsible for the sulfation of lutropin oligosaccharides in pituitary and carbonic anhydrase VI oligosaccharides in submaxillary gland. This GalNAc-4-sulfotransferase has an apparent molecular mass of 128 kDa and can be specifically photoaffinity radiolabeled with 3',5'-ADP, a competitive inhibitor of sulfotransferase activity. The acceptor specificity of this GalNAc-4-sulfotransferase indicates that it is able to transfer sulfate to terminal GalNAc beta 1,4GlcNAc on both N- and O-glycosidically linked oligosaccharides, suggesting that this enzyme is also responsible for the sulfation of O-linked glycans on proopiomelanocortin.
authors.affiliation: Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: L V
authors.initials: LV
authors.lastname: Hooper
authors.forename: O
authors.initials: O
authors.lastname: Hindsgaul
authors.forename: J U
authors.initials: JU
authors.lastname: Baenziger
mesh_terms: D000244:Adenosine Diphosphate; D000345:Affinity Labels; D000818:Animals; D002240:Carbohydrate Sequence; D002256:Carbonic Anhydrases / Q000378:metabolism; D002417:Cattle; D007986:Luteinizing Hormone / Q000378:metabolism; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism; D011333:Pro-Opiomelanocortin / Q000378:metabolism; D013363:Submandibular Gland / Q000201:enzymology*; D013379:Substrate Specificity; D015238:Sulfotransferases / Q000302:isolation & purification / Q000378:metabolism* / Q000528:radiation effects; D013463:Sulfuric Acid Esters / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D000345:Affinity Labels; D009844:Oligosaccharides; D013463:Sulfuric Acid Esters; D000244:Adenosine Diphosphate; D011333:Pro-Opiomelanocortin; D007986:Luteinizing Hormone; C092527:N-acetylgalactosamine-4-sulfotransferase; D015238:Sulfotransferases; D002256:Carbonic Anhydrases