Mannosyl-oligosaccharide glucosidase

Mannosyl-oligosaccharide glucosidase
Identifiers
EC number 3.2.1.106
CAS number 78413-07-7
Databases
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum

Mannosyl-oligosaccharide glucosidase (MOGS) (EC 3.2.1.106, processing alpha-glucosidase I, Glc3Man9NAc2 oligosaccharide glucosidase, trimming glucosidase I, GCS1) is an enzyme with systematic name mannosyl-oligosaccharide glucohydrolase.[1][2][3][4][5] MOGS is a transmembrane protein found in the membrane of the endoplasmic reticulum of eukaryotic cells. Biologically, it functions within the N-glycosylation pathway.

Enzyme mechanism

MOGS is a glycoside hydrolase enzyme, belonging to Family 63 as classified within the Carbohydrate-Active Enzyme database.[6]

This enzyme catalyses the following chemical reaction:

Exohydrolysis of the non-reducing terminal glucose residue in the mannosyl-oligosaccharide glycan Glc3Man9GlcNAc2

This reaction is the first trimming step in the N-glycosylation pathway. Prior to this, the glycan was co-translationally attached to a nascent protein by the oligosaccharyltransferase complex. MOGS removes the terminal glucose residue, leaving the glycoprotein linked to Glc2Man9GlcNAc2, which can then serve as a substrate for glucosidase II.

Substrate Specificity

MOGS is highly specific to the oligosaccharide in its biological substrate in the N-glycosylation pathway. Eukaryotic MOGS does not cleave simple substrates such as p-nitrophenyl glucose, and it also shows no activity to the α(1→3) linkage present at the terminus of Glc1-2Man9GlcNAc2.[7][8][9] Furthermore, the minimum substrate is the glucotriose molecule (Glc-α(1→2)-Glc-α(1→3)-Glc), linked as in its native Glc3Man9GlcNAc2 substrate. Kojibiose, the disaccharide Glc-α(1→2)-Glc, acts as a weak inhibitor on plant, animal, and yeast MOGS.[8][10][11][12]

MOGS also acts to lesser extent on the corresponding glycolipids and glycopeptides.

References

  1. ↑ Elting, J.J.; Chen, W.W.; Lennarz, J. (1980). "Characterization of a glucosidase involved in an initial step in the processing of oligosaccharide chains". J. Biol. Chem. 255: 2325–2331. PMID 7358674.
  2. ↑ Grinna, L.S.; Robbins, P.W. (1979). "Glycoprotein biosynthesis. Rat liver microsomal glucosidases which process oligosaccharides". J. Biol. Chem. 254: 8814–8818. PMID 479161.
  3. ↑ Kilker, R.D.; Saunier, B.; Tkacz, J.S.; Herscovics, A. (1981). "Partial purification from Saccharomyces cerevisiae of a soluble glucosidase which removes the terminal glucose from the oligosaccharide Glc3Man9GlcNAc2". J. Biol. Chem. 256: 5299–5603. PMID 7014569.
  4. ↑ Grinna, L.S.; Robbins, P.W. (1980). "Substrate specificities of rat liver microsomal glucosidases which process glycoproteins". J. Biol. Chem. 255: 2255–2258. PMID 7358666.
  5. ↑ Mark, M.J.; Kornfeld, S. (1980). "Partial purification and characterization of the glucosidases involved in the processing of asparagine-linked oligosaccharides". Arch. Biochem. Biophys. 199: 249–258. doi:10.1016/0003-9861(80)90278-7. PMID 7356331.
  6. ↑ "CAZy - GH63". www.cazy.org. Retrieved 2016-04-05.
  7. ↑ Vijay, I. K.; Shailubhai, K.; Dong-Yu, B.; Pratta, M. A.; Saxena, S. (1988-04-01). "Studies on the biosynthesis and regulation of asparagine-linked glycoproteins in the lactating mammary gland". Indian Journal of Biochemistry & Biophysics. 25 (1-2): 127–132. ISSN 0301-1208. PMID 2846425.
  8. 1 2 Bause, Ernst; Erkens, Rainer; Schweden, Jürgen; Jaenicke, Lothar (1986-10-06). "Purification and characterization of trimming glucosidase I from Saccharomyces cerevisiae". FEBS Letters. 206 (2): 208–212. doi:10.1016/0014-5793(86)80982-6.
  9. ↑ Shailubhai, K.; Saxena, E. S.; Balapure, A. K.; Vijay, I. K. (1990-06-15). "Developmental regulation of glucosidase I, an enzyme involved in the processing of asparagine-linked glycoproteins in rat mammary gland". The Journal of Biological Chemistry. 265 (17): 9701–9706. ISSN 0021-9258. PMID 2190984.
  10. ↑ Zeng, Y. C.; Elbein, A. D. (1998-07-01). "Purification to homogeneity and properties of plant glucosidase I". Archives of Biochemistry and Biophysics. 355 (1): 26–34. doi:10.1006/abbi.1998.0717. ISSN 0003-9861. PMID 9647663.
  11. ↑ Schweden, J.; Borgmann, C.; Legler, G.; Bause, E. (1986-07-01). "Characterization of calf liver glucosidase I and its inhibition by basic sugar analogs". Archives of Biochemistry and Biophysics. 248 (1): 335–340. doi:10.1016/0003-9861(86)90429-7. ISSN 0003-9861. PMID 2942110.
  12. ↑ Ugalde, R. A.; Staneloni, R. J.; Leloir, L. F. (1980-12-01). "Microsomal glucosidases of rat liver. Partial purification and inhibition by disaccharides". European journal of biochemistry / FEBS. 113 (1): 97–103. ISSN 0014-2956. PMID 7460954.
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