ExplorEnz: EC 2.4.99.18

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2.4.99.18

Accepted name:

dolichyl-diphosphooligosaccharide—protein glycotransferase

Reaction:

dolichyl diphosphooligosaccharide + [protein]-L-asparagine = dolichyl diphosphate + a glycoprotein with the oligosaccharide chain attached by N-β-D-glycosyl linkage to a protein L-asparagine

For diagram of glycoprotein biosynthesis, click here

Other name(s):

dolichyldiphosphooligosaccharide-protein glycosyltransferase; asparagine N-glycosyltransferase; dolichyldiphosphooligosaccharide-protein oligosaccharyltransferase; dolichylpyrophosphodiacetylchitobiose-protein glycosyltransferase; oligomannosyltransferase; oligosaccharide transferase; dolichyldiphosphoryloligosaccharide-protein oligosaccharyltransferase; dolichyl-diphosphooligosaccharide:protein-L-asparagine oligopolysaccharidotransferase; STT3

Systematic name:

dolichyl-diphosphooligosaccharide:protein-L-asparagine N-β-D-oligopolysaccharidotransferase

Comments:

Occurs in eukaryotes that form a glycoprotein by the transfer of a glucosyl-mannosyl-glucosamine polysaccharide to the side-chain of an L-asparagine residue in the sequence -Asn-Xaa-Ser- or -Asn-Xaa-Thr- (Xaa not Pro) in nascent polypeptide chains. The basic oligosaccharide is the tetradecasaccharide Glc₃Man₉GlcNAc₂ (for diagram click here). However, smaller oligosaccharides derived from it and oligosaccharides with additional monosaccharide units attached may be involved. See ref [2] for a review of N-glycoproteins in eukaryotes. Man₃GlcNAc₂ seems to be common for all of the oligosaccharides involved with the terminal N-acetylglucosamine linked to the protein L-asparagine. Occurs on the cytosolic face of the endoplasmic reticulum. The dolichol involved normally has 14-21 isoprenoid units with two trans double-bonds at the ω end, and the rest of the double-bonds in cis form.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 75302-32-8

References:

1.	Das, R.C. and Heath, E.C. Dolichyldiphosphoryloligosaccharide-protein oligosaccharyltransferase; solubilization, purification, and properties. Proc. Natl. Acad. Sci. USA 77 (1980) 3811–3815. [DOI] [PMID: 6933437]
2.	Song, W., Henquet, M.G., Mentink, R.A., van Dijk, A.J., Cordewener, J.H., Bosch, D., America, A.H. and van der Krol, A.R. N-glycoproteomics in plants: perspectives and challenges. J Proteomics 74 (2011) 1463–1474. [DOI] [PMID: 21605711]

[EC 2.4.99.18 created 1984 as EC 2.4.1.119, transferred 2012 to EC 2.4.99.18]