Reaction: GlcMan9GlcNAc2-[protein] + H2O = Man8GlcNAc2-[protein] (isomer 8A1,2,3B1,2) + α-D-glucosyl-(1→3)-α-D-mannopyranose
Glossary: GlcMan9GlcNAc2-[protein] = {α-D-Glc-(1→3)-α-D-Man-(1→2)-α-D-Man-(1→2)-α-D-Man-(1→3)-[α-D-Man-(1→2)-α-D-Man-(1→3)-[α-D-Man-(1→2)-α-D-Man-(1→6)]-α-D-Man-(1→6)]-β-D-Man-(1→4)-β-D-GlcNAc-(1→4)-α-D-GlcNAc}-N-Asn-[protein]
Man8GlcNAc2-[protein] (isomer 8A1,2,3B1,2) = {α-D-Man-(1→2)-α-D-Man-(1→3)-[α-D-Man-(1→2)-α-D-Man-(1→3)-[α-D-Man-(1→2)-α-D-Man-(1→6)]-α-D-Man-(1→6)]-β-D-Man-(1→4)-β-D-GlcNAc-(1→4)-α-D-GlcNAc}-N-Asn-[protein]
Other name(s): glucosylmannosidase; endo-α-D-mannosidase; endo-α-mannosidase; endomannosidase; glucosyl mannosidase; MANEA (gene name); glycoprotein glucosylmannohydrolase
Systematic name: glycoprotein glucosylmannohydrolase (configuration-retaining)
Comments: The enzyme catalyses the hydrolysis of the terminal α-D-glucosyl-(1→3)-D-mannosyl unit from the GlcMan9(GlcNAc)2 oligosaccharide component of N-glucosylated proteins during their processing in the Golgi apparatus. The name for the isomer is based on a nomenclature proposed by Prien et al [7].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 108022-16-8
References:
1. Lubas, W.A. and Spiro, R.G. Golgi endo-α-D-mannosidase from rat liver, a novel N-linked carbohydrate unit processing enzyme. J. Biol. Chem. 262 (1987) 3775-3781. [PMID: 3818665]
2. Tulsiani, D.R.P., Coleman, V.P. and Touster, O. Asparagine-linked glycoprotein biosynthesis in rat brain: identification of glucosidase I, glucosidase II, and endomannosidase (glucosyl mannosidase). Arch. Biochem. Biophys. 277 (1990) 114-121. [PMID: 2407194]
3. Hiraizumi, S., Spohr, U. and Spiro, R.G. Ligand affinity chromatographic purification of rat liver Golgi endomannosidase. J. Biol. Chem. 269 (1994) 4697-4700. [PMID: 8106437]
4. Spiro, M.J., Bhoyroo, V.D. and Spiro, R.G. Molecular cloning and expression of rat liver endo-α-mannosidase, an N-linked oligosaccharide processing enzyme. J. Biol. Chem. 272 (1997) 29356-29363. [PMID: 9361017]
5. Hamilton, S.R., Li, H., Wischnewski, H., Prasad, A., Kerley-Hamilton, J.S., Mitchell, T., Walling, A.J., Davidson, R.C., Wildt, S. and Gerngross, T.U. Intact α-1,2-endomannosidase is a typical type II membrane protein. Glycobiology 15 (2005) 615-624. [PMID: 15677381]
6. Hardt, B., Volker, C., Mundt, S., Salska-Navarro, M., Hauptmann, M. and Bause, E. Human endo-α1,2-mannosidase is a Golgi-resident type II membrane protein. Biochimie 87 (2005) 169-179. [PMID: 15760709]
7. Prien, J.M., Ashline, D.J., Lapadula, A.J., Zhang, H. and Reinhold, V.N. The high mannose glycans from bovine ribonuclease B isomer characterization by ion trap MS. J Am Soc Mass Spectrom 20 (2009) 539-556. [PMID: 19181540]