ExplorEnz: EC 3.2.1.210

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3.2.1.210

Accepted name:

endoplasmic reticulum Man₈GlcNAc₂ 1,2-α-mannosidase

Reaction:

Man₈GlcNAc₂-[protein] (isomer 8A_1,2,3B_1,3) + H₂O = Man₇GlcNAc₂-[protein] (isomer 7A_1,2,3B₃) + D-mannopyranose

Glossary:

Man₈GlcNAc₂-[protein] (isomer 8A_1,2,3B_1,3) = {α-D-Man-(1→2)-α-D-Man-(1→2)-α-D-Man-(1→3)-[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]
Man₇GlcNAc₂-[protein] (isomer 7A_1,2,3B₃) = {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→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):

MNL1 (gene name)

Systematic name:

Man₈GlcNAc₂-[protein] 2-α-mannohydrolase (configuration-inverting)

Comments:

In yeast this activity is catalysed by a dedicated enzyme that processes unfolded protein-bound Man₈GlcNAc₂ N-glycans within the endoplasmic reticulum to Man₇GlcNAc₂. The exposed α-1,6-linked mannose residue in the product enables the recognition by the YOS9 lectin, targeting the proteins for degradation. In mammalian cells this activity is part of the regular processing of N-glycosylated proteins, and is not associated with protein degradation. It is carried out by EC 3.2.1.113, Golgi mannosyl-oligosaccharide 1,2-α-mannosidase. The names of the isomers listed here are based on a nomenclature system proposed by Prien et al [5].

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc

References:

1.	Nakatsukasa, K., Nishikawa, S., Hosokawa, N., Nagata, K. and Endo, T. Mnl1p, an α -mannosidase-like protein in yeast Saccharomyces cerevisiae, is required for endoplasmic reticulum-associated degradation of glycoproteins. J. Biol. Chem. 276 (2001) 8635–8638. [PMID: 11254655]
2.	Jakob, C.A., Bodmer, D., Spirig, U., Battig, P., Marcil, A., Dignard, D., Bergeron, J.J., Thomas, D.Y. and Aebi, M. Htm1p, a mannosidase-like protein, is involved in glycoprotein degradation in yeast. EMBO Rep. 2 (2001) 423–430. [PMID: 11375935]
3.	Quan, E.M., Kamiya, Y., Kamiya, D., Denic, V., Weibezahn, J., Kato, K. and Weissman, J.S. Defining the glycan destruction signal for endoplasmic reticulum-associated degradation. Mol. Cell 32 (2008) 870–877. [PMID: 19111666]
4.	Clerc, S., Hirsch, C., Oggier, D.M., Deprez, P., Jakob, C., Sommer, T. and Aebi, M. Htm1 protein generates the N-glycan signal for glycoprotein degradation in the endoplasmic reticulum. J. Cell Biol. 184 (2009) 159–172. [PMID: 19124653]
5.	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. [DOI] [PMID: 19181540]
6.	Chantret, I., Kodali, V.P., Lahmouich, C., Harvey, D.J. and Moore, S.E. Endoplasmic reticulum-associated degradation (ERAD) and free oligosaccharide generation in Saccharomyces cerevisiae. J. Biol. Chem. 286 (2011) 41786–41800. [PMID: 21979948]

[EC 3.2.1.210 created 2019]