| Entry |
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| Name |
N-Glycan biosynthesis |
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| Description |
N-glycans or asparagine-linked glycans are major constituents of glycoproteins in eukaryotes. N-glycans are covalently attached to asparagine with the consensus sequence of Asn-X-Ser/Thr by an N-glycosidic bond, GlcNAc b1- Asn. Biosynthesis of N-glycans begins on the cytoplasmic face of the ER membrane with the transferase reaction of UDP-GlcNAc and the lipid-like precursor P-Dol (dolichol phosphate) to generate GlcNAc a1- PP-Dol. After sequential addition of monosaccharides by ALG glycosyltransferases [MD: M00055], the N-glycan precursor is attached by the OST (oligosaccharyltransferase) complex to the polypeptide chain that is being synthesized and translocated through the ER membrane. The protein-bound N-glycan precursor is subsequently trimmed, extended, and modified in the ER and Golgi by a complex series of reactions catalyzed by membrane-bound glycosidases and glycosyltransferases. N-glycans thus synthesized are classified into three types: high-mannose type, complex type, and hybrid type. Defects in N-glycan biosynthesis lead to a variety of human diseases known as congenital disorders of glycosylation [DS: H00118 H00119].
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| Class |
Metabolism; Glycan biosynthesis and metabolism
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| Pathway map |
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| Module |
| M00072 | N-glycosylation by oligosaccharyltransferase [PATH:rn00510] |
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| Other DBs |
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| Reaction |
| R01003 | dolichyl-phosphate phosphohydrolase |
| R01004 | dolichyl-diphosphate phosphohydrolase |
| R01005 | UDPglucose:dolichyl-phosphate beta-D-glucosyltransferase |
| R01006 | dolichyl-beta-D-glucosyl-phosphate dolichylphosphohydrolase |
| R01009 | GDPmannose:dolichyl-phosphate O-beta-D-mannosyltransferase |
| R01018 | CTP:dolichol O-phosphotransferase |
| R05969 | UDP-N-acetyl-D-glucosamine:dolichyl-phosphate N-acetyl-D-glucosamine phosphotransferase |
| R05980 | Glc2Man9GlcNAc2-[protein] 3-alpha-glucohydrolase (configuration-inverting) |
| R05981 | GlcMan9GlcNAc2-[protein] 3-alpha-glucohydrolase (configuration-inverting) |
| R05989 | UDP-galactose:N-acetyl-beta-D-glucosaminylglycopeptide beta-1,4-galactosyltransferase |
| R05990 | CMP-N-acetylneuraminate:beta-D-galactosyl 1,4-N-acetyl-beta-D-glucosamine alpha 2,6-N-acetylneuraminyltransferase |
| R06127 | GDP-mannose:glycolipid 1,2-alpha-D-mannosyltransferase |
| R06128 | GDP-mannose:glycolipid 1,2-alpha-D-mannosyltransferase |
| R06238 | GDP-D-mannose:D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol alpha-6-mannosyltransferase |
| R06262 | dolichyl beta-D-glucosyl phosphate:D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->6)]-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol alpha-1,3-glucosyltransferase |
| R06263 | dolichyl beta-D-glucosyl phosphate:D-Glc-alpha-(1->3)-D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->6)]-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol alpha-1,3-glucosyltransferase |
| R06264 | dolichyl beta-D-glucosyl phosphate:D-Glc-alpha-(1->3)-D-Glc-alpha-(1->3)-D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->6)]-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol alpha-1,2-glucosyltransferase |
| R06722 | alpha 1,2-mannosyloligosaccharide alpha-D-mannohydrolase |
| R13402 | ditrans,polycis-polyprenol:NAD+ oxidoreductase |
| R13403 | dolichol:NADP+ oxidoreductase |
| R13444 | dolichal:NADP+ 2,3-oxidoreductase |
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| Compound |
| C01246 | Dolichyl beta-D-glucosyl phosphate |
| C03862 | Dolichyl phosphate D-mannose |
| C22974 | ditrans,polycis-Polyprenal |
| G00001 | N-Acetyl-D-glucosaminyldiphosphodolichol |
| G00002 | N,N'-Chitobiosyldiphosphodolichol |
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| Reference |
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| Authors |
Schutzbach JS. |
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| Title |
The role of the lipid matrix in the biosynthesis of dolichyl-linked oligosaccharides. |
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| Journal |
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| Reference |
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| Authors |
Oriol R, Martinez-Duncker I, Chantret I, Mollicone R, Codogno P. |
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| Title |
Common origin and evolution of glycosyltransferases using Dol-P-monosaccharides as donor substrate. |
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| Journal |
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| Reference |
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| Authors |
Thiel C, Schwarz M, Peng J, Grzmil M, Hasilik M, Braulke T, Kohlschutter A, von Figura K, Lehle L, Korner C. |
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| Title |
A new type of congenital disorders of glycosylation (CDG-Ii) provides new insights into the early steps of dolichol-linked oligosaccharide biosynthesis. |
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| Journal |
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| Reference |
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| Authors |
Cipollo JF, Trimble RB, Chi JH, Yan Q, Dean N. |
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| Title |
The yeast ALG11 gene specifies addition of the terminal alpha 1,2-Man to the Man5GlcNAc2-PP-dolichol N-glycosylation intermediate formed on the cytosolic side of the endoplasmic reticulum. |
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| Journal |
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| Reference |
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| Authors |
Frank CG, Aebi M. |
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| Title |
ALG9 mannosyltransferase is involved in two different steps of lipid-linked oligosaccharide biosynthesis. |
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| Journal |
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| Reference |
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| Authors |
O'Reilly MK, Zhang G, Imperiali B. |
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| Title |
In vitro evidence for the dual function of Alg2 and Alg11: essential mannosyltransferases in N-linked glycoprotein biosynthesis. |
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| Journal |
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Related
pathway |
| rn00051 | Fructose and mannose metabolism |
| rn00513 | Various types of N-glycan biosynthesis |
| rn00515 | Mannose type O-glycan biosynthesis |
| rn00520 | Amino sugar and nucleotide sugar metabolism |
| rn00563 | Glycosylphosphatidylinositol (GPI)-anchor biosynthesis |
| rn00900 | Terpenoid backbone biosynthesis |
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| KO pathway |
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