EC - α-1,3-mannosyl-glycoprotein 2-β-N-acetylglucosaminyltransferase

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IntEnz Enzyme Nomenclature


Accepted name:
α-1,3-mannosyl-glycoprotein 2-β-N-acetylglucosaminyltransferase
Other names:
N-acetylglucosaminyltransferase I
N-glycosyl-oligosaccharide-glycoprotein N-acetylglucosaminyltransferase I
α-1,3-mannosyl-glycoprotein β-1,2-N-acetylglucosaminyltransferase
UDP-N-acetylglucosaminyl:α-1,3-D-mannoside-β-1,2-N-acetylglucosaminyltransferase I
UDP-N-acetylglucosaminyl:α-3-D-mannoside β-1,2-N-acetylglucosaminyltransferase I
uridine diphosphoacetylglucosamine-α-1,3-mannosylglycoprotein β-1,2-N-acetylglucosaminyltransferase
GlcNAc-T I
UDP-N-acetyl-D-glucosamine:3-(α-D-mannosyl)-β-D-mannosyl-glycoprotein 2-β-N-acetyl-D-glucosaminyltransferase
Systematic name:
UDP-N-acetyl-α-D-glucosamine:α-D-mannosyl-(1→3)-β-D-mannosyl-glycoprotein 2-β-Nacetyl-D-glucosaminyltransferase (configuration-inverting)



The enzyme, found in plants and animals, participates in the processing of N-glycans in the Golgi apparatus. Its action is required before the other N-acetylglucosaminyltransferases involved in the process (GlcNAcT-II through VI) can act. While the natural substrate (produced by EC, mannosyl-oligosaccharide 1,2-α-mannosidase) is described here, the minimal substrate recognized by the enzyme is α-D-Man-(1→3)-β-D-Man-R.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0003827
CAS Registry Number: 102576-81-8


  1. Harpaz, N. and Schachter, H.
    Control of glycoprotein synthesis. Bovine colostrum UDP-N-acetylglucosamine:α-D-mannoside β2-N-acetylglucosaminyltransferase I. Separation from UDP-N-acetylglucosamine:α-D-mannoside β2-N-acetylglucosaminyltransferase II, partial purification, and substrate specificity.
    J. Biol. Chem. 255 : 4885-4893 (1980). [PMID: 6445358]
  2. Mendicino, J., Chandrasekaran, E.V., Anumula, K.R. and Davila, M.
    Isolation and properties of α-D-mannose:β-1,2-N-acetylglucosaminyltransferase from trachea mucosa.
    Biochemistry 20 : 967-976 (1981). [PMID: 6452163]
  3. Miyagi, T. and Tsuiki, S.
    Studies on UDP-N-acetylglucosamine:α-mannoside β-N-acetylglucosaminyltransferase of rat liver and hepatomas.
    Biochim. Biophys. Acta 661 : 148-157 (1981). [PMID: 6170335]
  4. Oppenheimer, C.L., Eckhardt, A.E. and Hill, R.L.
    The nonidentity of porcine N-acetylglucosaminyltransferases I and II.
    J. Biol. Chem. 256 : 11477-11482 (1981). [PMID: 6457827]
  5. Oppenheimer, C.L. and Hill, R.L.
    Purification and characterization of a rabbit liver α1→3 mannoside β1→2 N-acetylglucosaminyltransferase.
    J. Biol. Chem. 256 : 799-804 (1981). [PMID: 6450208]
  6. 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]
  7. Vella, G.J., Paulsen, H. and Schachter, H.
    Control of glycoprotein synthesis. IX. A terminal Man αl-3Man β1- sequence in the substrate is the minimum requirement for UDP-N-acetyl-D-glucosamine:α-D-mannoside (GlcNAc to Man α1-3) β2-N-acetylglucosaminyltransferase I.
    Can. J. Biochem. Cell Biol. 62 : 409-417 (1984). [PMID: 6235906]
  8. Ünligil, U.M., Zhou, S., Yuwaraj, S., Sarkar, M., Schachter, H. and Rini, J.M.
    X-ray crystal structure of rabbit N-acetylglucosaminyltransferase I: catalytic mechanism and a new protein superfamily.
    EMBO J. 19 : 5269-5280 (2000). [PMID: 11032794]

[EC created 1983, modified 2001 (EC created 1972, part incorporated 1984)]