Flipping of the N-glycan precursor to inside the ER

Stable Identifier
Reaction [transition]
Homo sapiens
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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).

Literature References
PubMed ID Title Journal Year
18313027 Human RFT1 deficiency leads to a disorder of N-linked glycosylation

Hennet, T, Haeuptle, MA, Kastaniotis, AJ, Neupert, C, Pujol, FM, Winchester, B, Aebi, M

Am J Hum Genet 2008
18597486 Distinct flippases translocate glycerophospholipids and oligosaccharide diphosphate dolichols across the endoplasmic reticulum

Sanyal, S, Menon, AK, Frank, CG

Biochemistry 2008
11807558 Translocation of lipid-linked oligosaccharides across the ER membrane requires Rft1 protein

Walter, P, Valvano, MA, Helenius, J, Marolda, CL, Aebi, M, Ng, DT

Nature 2002
Catalyst Activity

glycolipid floppase activity of RFT1 [endoplasmic reticulum membrane]

Inferred From
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