Alternative endo-mannosidase I route

Stable Identifier
Reaction [transition]
Homo sapiens
Locations in the PathwayBrowser
SVG |   | PPTX  | SBGN
Click the image above or here to open this reaction in the Pathway Browser
The layout of this reaction may differ from that in the pathway view due to the constraints in pathway layout
Cells exposed to castanospermine or 1-deoxynojirimycin (inhibitors of the glucosidase enzymes GCS1 and GANAB), are still able to carry out glycosylation and produce complex glycans. This is due to the existence of an alternative route catalyzed by the enzyme endomannosidase (Moore and Spiro, 1990).
Glycoproteins that pass through this route probably skip or have a reduced interaction with the Calnexin/Calreticulin cycle, and are transported to the cis-golgi through a route that has not been described yet (probably through the general ER to Golgi flow). Here, the Endomannosidase enzyme, which resides on the Golgi membrane (Hardt et al 2005; Hamilton et al 2005) is able to remove the tri-, di-, or mono-glucose substituted mannose on branch A, leading to a deglucosylated N-glycan structure (Lubas and Spiro, 1988).
Literature References
PubMed ID Title Journal Year
15760709 Human endo-alpha1,2-mannosidase is a Golgi-resident type II membrane protein

Hardt, B, Hauptmann, M, Bause, E, Völker, C, Salska-Navarro, M, Mundt, S

Biochimie 2005
2165493 Demonstration that Golgi endo-alpha-D-mannosidase provides a glucosidase-independent pathway for the formation of complex N-linked oligosaccharides of glycoproteins

Spiro, RG, Moore, SE

J Biol Chem 1990
3346233 Evaluation of the role of rat liver Golgi endo-alpha-D-mannosidase in processing N-linked oligosaccharides

Spiro, RG, Lubas, WA

J Biol Chem 1988
15677381 Intact {alpha}-1,2-endomannosidase is a typical type II membrane protein

Kerley-Hamilton, JS, Walling, AJ, Wildt, S, Hamilton, SR, Mitchell, T, Li, H, Davidson, RC, Wischnewski, H, Gerngross, TU, Prasad, A

Glycobiology 2005
Catalyst Activity

glycoprotein endo-alpha-1,2-mannosidase activity of MANEA [Golgi membrane]

Orthologous Events
Cite Us!