Peptide-specific transfer of N-acetylgalactosamine to O-linked glycans by the glycosyltransferases β1,4-N-acetylgalactosaminyl transferase 3 (β4GalNAc-T3) and β4GalNAc-T4.
N- and O-linked oligosaccharides on pro-opiomelanocortin both bear the unique terminal sequence SO(4)-4-GalNAcβ1,4GlcNAcβ. We previously demonstrated that protein-specific transfer of GalNAc to N-linked oligosaccharides on glycoprotein substrates is dependent on the presence of both an oligosaccharide acceptor and a peptide recognition motif consisting of a cluster of basic amino acids. We characterized how two β1,4-N-acetylgalactosaminyltransferases, β4GalNAc-T3 and β4GalNAc-T4, require the presence of both the peptide recognition motif and the N-linked oligosaccharide acceptors to transfer GalNAc in β1,4-linkage to GlcNAc in vivo and in vitro. We now show that β4GalNAc-T3 and β4GalNAc-T4 are able to utilize the same peptide motif to selectively add GalNAc to β1,6-linked GlcNAc in core 2 O-linked oligosaccharide structures to form Galβ1,3(GalNAcβ1,4GlcNAcβ1,6)GalNAcαSer/Thr. The β1,4-linked GalNAc can be further modified with 4-linked sulfate by either GalNAc-4-sulfotransferase 1 (GalNAc-4-ST1) (CHST8) or GalNAc-4-ST2 (CHST9) or with α2,6-linked N-acetylneuraminic acid by α2,6-sialyltransferase 1 (ST6Gal1), thus generating a family of unique GalNAcβ1,4GlcNAcβ (LacdiNAc)-containing structures on specific glycoproteins.
Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Dorothy
D
Fiete
Mary
M
Beranek
Jacques U
JU
Baenziger
D000117:Acetylglucosamine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D006023:Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D017350:N-Acetylgalactosaminyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012799:Sialyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015238:Sulfotransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
D000117:Acetylglucosamine; D015703:Antigens, CD; D006023:Glycoproteins; D017350:N-Acetylgalactosaminyltransferases; D010455:Peptides; D012799:Sialyltransferases; D015238:Sulfotransferases; C093493:ST6GAL1 protein, human; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase; C498300:CHST9 protein, human