EC - β-1,4-mannosyl-glycoprotein 4-β-N-acetylglucosaminyltransferase

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IntEnz Enzyme Nomenclature


Accepted name:
β-1,4-mannosyl-glycoprotein 4-β-N-acetylglucosaminyltransferase
Other names:
N-acetylglucosaminyltransferase III
N-glycosyl-oligosaccharide-glycoprotein N-acetylglucosaminyltransferase III
β-1,4-mannosyl-glycoprotein β-1,4-N-acetylglucosaminyltransferase
uridine diphosphoacetylglucosamine-glycopeptide β4-acetylglucosaminyltransferase III
MGAT3 (gene name)
UDP-N-acetyl-D-glucosamine:β-D-mannosyl-glycoprotein 4-β-N-acetyl-D-glucosaminyltransferase
Systematic name:
UDP-N-acetyl-α-D-glucosamine:β-D-mannosyl-glycoprotein 4-β-N-acetyl-D-glucosaminyltransferase (configuration-inverting)



The enzyme, found in vertebrates, participates in the processing of N-glycans in the Golgi apparatus. The residue added by the enzyme at position 4 of the β-linked mannose of the trimannosyl core of N-glycans is known as a bisecting GlcNAc. Unlike GlcNAc residues added to other positions, it is not extended or modified. In addition, its presence prevents the action of other branching enzymes involved in the process such as GlcNAc-T IV (EC and GlcNAc-T V (EC, and thus increased activity of GlcNAc-T III leads to a decrease in highly branched N-glycan structures. Formerly EC

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0003830
CAS Registry Number: 83744-93-8


  1. Narasimhan, S.
    Control of glycoprotein synthesis. UDP-GlcNAc:glycopeptide β4-N-acetylglucosaminyltransferase III, an enzyme in hen oviduct which adds GlcNAc in β1-4 linkage to the β-linked mannose of the trimannosyl core of N-glycosyl oligosaccharides.
    J. Biol. Chem. 257 : 10235-10242 (1982). [PMID: 6213618]
  2. Schachter, H., Narasimhan, S., Gleeson, P. and Vella, G.
    Glycosyltransferases involved in elongation of N-glycosidically linked oligosaccharides of the complex or N-acetyllactosamine type.
    Methods Enzymol. 98 : 98-134 (1983). [PMID: 6366476]
  3. Brockhausen, I., Carver, J. P., Schachter, H.
    Control of glycoprotein synthesis. The use of oligosaccharide substrates and HPLC to study the sequential pathway for N-acetylglucosaminyltransferases I, II, III, IV, V, and VI in the biosynthesis of highly branched N-glycans by hen oviduct membranes.
    Biochem. Cell Biol. 66 : 1134-1151 (1988). [PMID: 2975180]
  4. Nishikawa, A., Ihara, Y., Hatakeyama, M., Kangawa, K., Taniguchi, N.
    Purification, cDNA cloning, and expression of UDP-N-acetylglucosamine: beta-D-mannoside beta-1,4N-acetylglucosaminyltransferase III from rat kidney.
    J. Biol. Chem. 267 : 18199-18204 (1992). [PMID: 1325461]
  5. Ihara, Y., Nishikawa, A., Tohma, T., Soejima, H., Niikawa, N., Taniguchi, N.
    cDNA cloning, expression, and chromosomal localization of human N-acetylglucosaminyltransferase III (GnT-III).
    J. Biochem. 113 : 692-698 (1993). [PMID: 8370666]

[EC created 1984, modified 2001 (EC created 1972, part incorporated 1984)]