A necessary and sufficient determinant for protein-selective glycosylation in vivo.
A limited number of glycoproteins including luteinizing hormone and carbonic anhydrase-VI (CA6) bear N-linked oligosaccharides that are modified with beta1,4-linked N-acetylgalactosamine (GalNAc). The selective addition of GalNAc to these glycoproteins requires that the beta1,4-N-acetylgalactosaminyltransferase (betaGT) recognize both the oligosaccharide acceptor and a peptide recognition determinant on the substrate glycoprotein. We report here that two recently cloned betaGTs, betaGT3 and betaGT4, that are able to transfer GalNAc to GlcNAc in beta1,4-linkage display the necessary glycoprotein specificity in vivo. Both betaGTs transfer GalNAc to N-linked oligosaccharides on the luteinizing hormone alpha subunit and CA6 but not to those on transferrin (Trf). A single peptide recognition determinant encoded in the carboxyl-terminal 19-amino acid sequence of bovine CA6 mediates transfer of GalNAc to each of its two N-linked oligosaccharides. The addition of this 19-amino acid sequence to the carboxyl terminus of Trf confers full acceptor activity onto Trf for both betaGT3 and betaGT4 in vivo. The complete 19-amino acid sequence is required for optimal GalNAc addition in vivo, indicating that the peptide sequence is both necessary and sufficient for recognition by betaGT3 and betaGT4.
Miller
Erin
E
Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Fiete
Dorothy
D
Blake
Nicquet M J
NM
Beranek
Mary
M
Oates
Edward L
EL
Mi
Yiling
Y
Roseman
Daniel S
DS
Baenziger
Jacques U
JU
D000117:Acetylglucosamine / Q000235:genetics / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007986:Luteinizing Hormone / Q000235:genetics / Q000378:metabolism*; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D009844:Oligosaccharides / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D046188:Protein Modification, Translational / Q000502:physiology*; D013379:Substrate Specificity / Q000502:physiology; D014168:Transferrin / Q000235:genetics / Q000378:metabolism
D006023:Glycoproteins; D009844:Oligosaccharides; D010455:Peptides; D014168:Transferrin; D007986:Luteinizing Hormone; C480161:B4GALNT3 protein, human; C484901:B4GALNT4 protein, human; D017350:N-Acetylgalactosaminyltransferases; D002256:Carbonic Anhydrases; C477051:carbonic anhydrase VI; D000117:Acetylglucosamine