Transfer of N-glycan to the protein

Stable Identifier
R-HSA-446209
Type
Reaction [transition]
Species
Homo sapiens
Compartment
Locations in the PathwayBrowser
General
SVG |   | PPTX  | SBGN
Click the image above or here to open this reaction in the Pathway Browser
The layout of this reaction may differ from that in the pathway view due to the constraints in pathway layout

The 14-sugar N-glycan precursor (aka lipid-linked oligosaccharide, LLO), synthesized in the previous reactions, is attached in a single step to a nascent protein, releasing the dolichyl phosphate anchor and the as-yet unfolded glycoprotein. The reaction occurs cotranslationally as the growing peptide chain leaves a ribosome associated with the ER membrane and enters the ER lumen. This reaction is catalyzed by the oligosaccharyltransferase (OST) complex, comprising at least seven proteins; DAD1 (Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit DAD1), DDOST (OST48 in yeast), RPN1 (ribophorin 1), RPN2 (ribophorin 2), OST4, TUSC3 (N33), MAGT1 (magnesium transporter protein 1) and either STT3A or STT3B (Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit STT3A and B), which contain the catalytic domain (Kelleher & Gilmore 2006). A mutation in RPN2 is associated with CDG-Ix (Vleugels et al. 2009). The signal for glycosylation is the consensus sequence Asn - X - Thr/Ser, where the first amino acid is always Asn, the second can be any amino acid except for Pro, and the third position may be Thr, Ser or Cys, with a preference for the first (Breuer et al. 2001). Not all Asn - X - Thr/Ser sites are modified in vivo (Petrescu et al. 2004).

Literature References
PubMed ID Title Journal Year
19835842 Screening for OST deficiencies in unsolved CDG-I patients

Vleugels, W, Schollen, E, Foulquier, F, Matthijs, G

Biochem Biophys Res Commun 2009
11470266 Oligosaccharyltransferase is highly specific for the hydroxy amino acid in Asn-Xaa-Thr/Ser

Breuer, W, Klein, RA, Hardt, B, Bartoschek, A, Bause, E

FEBS Lett 2001
14514716 Statistical analysis of the protein environment of N-glycosylation sites: implications for occupancy, structure, and folding

Petrescu, AJ, Milac, AL, Petrescu, SM, Dwek, RA, Wormald, MR

Glycobiology 2004
16317064 An evolving view of the eukaryotic oligosaccharyltransferase

Kelleher, DJ, Gilmore, R

Glycobiology 2006
Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
dolichyl-diphosphooligosaccharide-protein glycotransferase activity of OST complex [endoplasmic reticulum membrane]
Physical Entity
Activity
Authored
Reviewed
Created