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Information on EC 3.2.1.113 - mannosyl-oligosaccharide 1,2-alpha-mannosidase

for references in articles please use BRENDA:EC3.2.1.113

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IUBMB Comments

This family of mammalian enzymes, located in the Golgi system, participates in the maturation process of N-glycans that leads to formation of hybrid and complex structures. The enzymes catalyse the hydrolysis of the four (1→2)-linked α-D-mannose residues from the Man9GlcNAc2 oligosaccharide attached to target proteins as described in reaction (1). Alternatively, the enzymes act on the Man8GlcNAc2 isomer formed by EC 3.2.1.209, endoplasmic reticulum Man9GlcNAc2 1,2-α-mannosidase, as described in reaction (2). The enzymes are type II membrane proteins, require Ca2+, and use an inverting mechanism. While all three human enzymes can catalyse the reactions listed here, some of the enzymes can additionally catalyse hydrolysis in an alternative order, generating additional isomeric intermediates, although the final product is the same. The names of the isomers listed here are based on a nomenclature system proposed by Prien et al .

The expected taxonomic range for this enzyme is: Eukaryota, Bacteria

Synonyms
mania, manic, mannosidase i, man1b1, man1a1, man9-mannosidase, man1c1, man1a2, golgi alpha-mannosidase i, mns1p, more

REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
Man6GlcNAc2-[protein] (isomer 6A1,2,3) + H2O = Man5GlcNAc2-[protein] + beta-D-mannopyranose
show the reaction diagram
(2c)
-
-
-
Man6GlcNAc2-[protein] (isomer 6A1,2B2) + H2O = Man5GlcNAc2-[protein] + beta-D-mannopyranose
show the reaction diagram
(1d)
-
-
-
Man7GlcNAc2-[protein] (isomer 7A1,2,3B1) + H2O = Man6GlcNAc2-[protein] (isomer 6A1,2,3) + beta-D-mannopyranose
show the reaction diagram
(2b)
-
-
-
Man7GlcNAc2-[protein] (isomer 7A1,2,3B2) + H2O = Man6GlcNAc2-[protein] (isomer 6A1,2B2) + beta-D-mannopyranose
show the reaction diagram
(1c)
-
-
-
Man8GlcNAc2-[protein] (isomer 8A1,2,3B1,2) + H2O = Man7GlcNAc2-[protein] (isomer 7A1,2,3B2) + beta-D-mannopyranose
show the reaction diagram
(1b)
-
-
-
Man8GlcNAc2-[protein] (isomer 8A1,2,3B1,3) + 3 H2O = Man5GlcNAc2-[protein] + 3 beta-D-mannopyranose
show the reaction diagram
(2)
-
-
-
Man8GlcNAc2-[protein] (isomer 8A1,2,3B1,3) + H2O = Man7GlcNAc2-[protein] (isomer 7A1,2,3B1) + beta-D-mannopyranose
show the reaction diagram
(2a)
-
-
-
Man9GlcNAc2-[protein] + 4 H2O = Man5GlcNAc2-[protein] + 4 beta-D-mannopyranose
show the reaction diagram
Man9GlcNAc2-[protein] + H2O = Man8GlcNAc2-[protein] (isomer 8A1,2,3B1,2) + beta-D-mannopyranose
show the reaction diagram
(1a)
-
-
-
PATHWAY SOURCE
PATHWAYS
MetaCyc
protein N-glycosylation processing phase (plants and animals)