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.
Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Erin
E
Miller
Dorothy
D
Fiete
Nicquet M J
NM
Blake
Mary
M
Beranek
Edward L
EL
Oates
Yiling
Y
Mi
Daniel S
DS
Roseman
Jacques U
JU
Baenziger
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