Defective MOGS does not cleave glucose from an N-glycosylated protein

Stable Identifier
Reaction [transition]
Homo sapiens
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After the lipid-linked oligosaccharide (LLO) precursor is attached to the protein, the outer alpha-1,2-linked glucose is removed by by mannosyl-oligosaccharide glucosidase (MOGS). This is a mandatory step for protein folding control and glycan extension. Defects in MOGS are associated with congenital disorder of glycosylation type IIb (MOGS-CDG, CDGIIb; MIM:606056), a multisystem disorder caused by a defect in glycoprotein biosynthesis and characterised by under-glycosylated serum glycoproteins. Mutations causing MOGS-CDG are R486T and F652L. Kinetic studies using cultured fibroblasts showed that the by mannosyl-oligosaccharide glucosidase activity in the patient's cells was < 1% of control activity (De Praeter et al. 2000, Voelker et al. 2002).
Literature References
PubMed ID Title Journal Year
10788335 A novel disorder caused by defective biosynthesis of N-linked oligosaccharides due to glucosidase I deficiency

Espeel, MF, Chan, NW, Nuytinck, LK, Martin, JJ, Gerwig, GJ, Kamerling, JP, Bause, E, De Praeter, CM, Breuer, W, Van Coster, RN, De Paepe, AM, Dacremont, GA, Vliegenthart, JF

Am J Hum Genet 2000
12145188 Processing of N-linked carbohydrate chains in a patient with glucosidase I deficiency (CDG type IIb)

Hardt, B, Kalz-Füller, B, Bause, E, De Praeter, CM, Breuer, W, Van Coster, RN, Völker, C

Glycobiology 2002
Catalyst Activity

Glc3Man9GlcNAc2 oligosaccharide glucosidase activity of MOGS mutants [endoplasmic reticulum membrane]

Normal reaction
Functional status

Loss of function of MOGS mutants [endoplasmic reticulum membrane]

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