Reaction: Flipping of the N-glycan precursor to inside the ER
- in pathway: Biosynthesis of the N-glycan precursor (dolichol lipid-linked oligosaccharide, LLO) and transfer to a nascent protein
The precursor of the N-glycan sugar, now in the form of (GlcNAc)2 (Man)5 (PP-Dol), is flipped across the ER membrane, moving it from the cytosolic side into the ER lumen. The exact mechanism of this translocation is not well understood: the protein RFT1 is known to be involved (Helenius et al. 2002), along with an unknown flippase, which is distinct from the one that flips the Dol-P linked precursors (Dol-P-Mannose and Dol-P-glucose) (Sanyal et al. 2008). Defects in RFT1 are associated with Congenital Disorder of Glycosylation 1N (CDG1N) (Haeuptle et al. 2008).
Reaction - small molecule participants:
(GlcNAc)2 (Man)5 (PP-Dol)1 [integral component of lumenal side of endoplasmic reticulum membrane]
(GlcNAc)2 (Man)5 (PP-Dol)1 [integral component of cytoplasmic side of endoplasmic reticulum membrane]
Reactome.org reaction link: R-HSA-446212
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Reaction input - small molecules:
glycan G00006
Reaction output - small molecules:
glycan G00006
Reactome.org link: R-HSA-446212