ENZYME entry: EC 3.2.1.209
| Accepted Name |
|---|
| endoplasmic reticulum Man9GlcNAc2 1,2-alpha-mannosidase.
|
| Reaction catalysed |
|---|
| H2O + N(4)-(alpha-D-Man-(1->2)-alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-[alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-[alpha-D-Man-(1->2)-alpha-D-Man-(1->6)]-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc)-L-asparaginyl-[protein] (N-glucan mannose isomer 9A1,2,3B1,2,3) <=> beta-D-mannose + N(4)-(alpha-D-Man-(1->2)-alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-[alpha-D-Man-(1->3)-[alpha-D-Man-(1->2)-alpha-D-Man-(1->6)]-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-beta-D-GlcNAc)-L-asparaginyl-[protein] (N-glucan mannose isomer 8A1,2,3B1,3) |
| Comment(s) |
|---|
- The enzyme, located in the endoplasmic reticulum, primarily trims a
single alpha-1,2-linked mannose residue from Man9GlcNAc2 to produce
Man8GlcNAc2 isomer 8A1,2,3B1,3 (the names of the isomers listed here
are based on a nomenclature system proposed by Prien et al
(pmid:19181540)).
- The removal of the single mannosyl residue occurs in all eukaryotes
as part of the processing of N-glycosylated proteins, and is
absolutely essential for further elongation of the outer chain of
properly-folded N-glycosylated proteins in yeast.
- In addition, the enzyme is involved in glycoprotein quality control
at the ER quality control compartment (ERQC), helping to target
misfolded glycoproteins for degradation.
- When present at very high concentrations in the ERQC, the enzyme can
trim the carbohydrate chain further to Man(5-6)GlcNAc2.
|
| Cross-references |
|---|
| BRENDA | 3.2.1.209 |
| EC2PDB | 3.2.1.209 |
| ExplorEnz | 3.2.1.209 |
| PRIAM enzyme-specific profiles | 3.2.1.209 |
| KEGG Ligand Database for Enzyme Nomenclature | 3.2.1.209 |
| IUBMB Enzyme Nomenclature | 3.2.1.209 |
| IntEnz | 3.2.1.209 |
| MEDLINE | Find literature relating to 3.2.1.209 |
| MetaCyc | 3.2.1.209 |
| Rhea expert-curated reactions | 3.2.1.209 |
| UniProtKB/Swiss-Prot |
|
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