Defective MAN1B1 does not hydrolyse 1,2-linked mannose (b branch)

Stable Identifier
Reaction [transition]
Homo sapiens
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Endoplasmic reticulum mannosyl-oligosaccharide 1,2-alpha-mannosidase (MAN1B1) normally trims single mannose residues from misfolded glycoproteins, targeting them for degradation and thus providing a quality control process for N-glycosylated proteins. Defects in MAN1B1 can cause mental retardation, autosomal recessive 15 (MRT15; MIM:614202), a disorder resulting in nonsyndromic moderate to severe mental retardation. It is characterised by significantly below average intellectual functioning associated with impaired adaptative behaviour during the developmental period (Rafiq et al. 2010, Rafiq et al. 2011). Mutations that can cause MRT15 are E397K, W473* and R334C (Rafiq et al. 2010, Rafiq et al. 2011).
Literature References
PubMed ID Title Journal Year
21763484 Mutations in the alpha 1,2-mannosidase gene, MAN1B1, cause autosomal-recessive intellectual disability

Ullmann, R, Mahmood, K, Ramiah, A, Ropers, HH, Ishak, GE, Garshasbi, M, Ansar, M, Puettmann, L, Weksberg, R, Xiang, Y, Ayub, M, Kahrizi, K, Kuss, AW, Vincent, JB, Khan, MA, Hu, H, Moremen, KW, Tzschach, A, Kerio, NA, Naeem, F, Najmabadi, H, Noor, A, Ali, G, Rafiq, MA

Am. J. Hum. Genet. 2011
20345473 Mapping of three novel loci for non-syndromic autosomal recessive mental retardation (NS-ARMR) in consanguineous families from Pakistan

Shaheen, N, Noor, A, Scherer, SW, Amin-ud-Din, M, Ansar, M, Khan, MA, Mowjoodi, A, Rafiq, MA, Marshall, CR, Ali, G, Vincent, JB, Feuk, L

Clin. Genet. 2010
Catalyst Activity

mannosyl-oligosaccharide 1,2-alpha-mannosidase activity of MAN1B1 mutants [endoplasmic reticulum quality control compartment]

Normal reaction
Functional status

Loss of function of MAN1B1 mutants [endoplasmic reticulum quality control compartment]

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