Reaction: ALG3 transfers Man to N-glycan precursor (GlcNAc)2 (Man)5 (PP-Dol)1
- in pathway: Biosynthesis of the N-glycan precursor (dolichol lipid-linked oligosaccharide, LLO) and transfer to a nascent protein
The sixth mannose is added to the N-glycan precursor. This reaction occurs in the ER lumen and uses a different mannose donor (dolichyl-phosphate-mannose) than the previous steps. It has been proposed that ALG3, along with all the mannosyl- and glucosyltransferases in the N-glycan biosynthesis pathway that use dolichyl-phosphate-mannose or dolichyl-phosphate-glucose as donor, derive from duplications of a common ancestral enzyme (Oriol et al. 2002). Defects in ALG3 are associated with Congenital Disorder of Glycosylation 1D (CDG1D) (Sun et al. 2005).
Reaction - small molecule participants:
DOLP [integral component of lumenal side of endoplasmic reticulum membrane]
(GlcNAc)2 (Man)6 (PP-Dol)1 [integral component of lumenal side of endoplasmic reticulum membrane]
DOLP-Man [integral component of lumenal side of endoplasmic reticulum membrane]
(GlcNAc)2 (Man)5 (PP-Dol)1 [integral component of lumenal side of endoplasmic reticulum membrane]
Reactome.org reaction link: R-HSA-446188
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Reaction input - small molecules:
dolichyl D-mannosyl phosphate(1-)
glycan G00006
Reaction output - small molecules:
dolichyl phosphate(2-)
glycan G10595
Reactome.org link: R-HSA-446188