1.2 Assembly of N-linked glycans occursin three major stages
1.2 Assembly of N-linked glycans occurs in three major stages
Three stages.Formationofalipid-linkedprecursoroligosaccharideen bloc (总的)transfer of the oligosaccharide tothe polypeptideProcessing of the oligosaccharide
Three#stages# • Forma2on#of#a#lipid%linked#precursor# oligosaccharide# • en#bloc#(总的)#transfer#of#the#oligosaccharide#to# the#polypep2de# • Processing#of#the#oligosaccharide#
3ProcessingInitial trimming ofAddition ofterminalsugarresiduessugarresiduesSecretion ordeliverytoplasmamembraneTrimmingandmodificationofbranchstructure2EnbloctransfertoproteinProteinsynthesis1Synthesisoflipid-linkedprecursoroligosaccharidePlasmaGolgi apparatusMembraneEndoplasmicreticulum
1.3 The precursor oligosaccharide for N-linked glycans is assembled on the lipiddolichol
1.3 The precursor oligosaccharide for Nlinked glycans is assembled on the lipid dolichol
A dolichol sugar that can serve as the donor inglycosyltransferaserxnsontheluminal（腔的）sideoftheendoplasmicreticulum（内质网）membrane.OHDolicholO=HO-P-OHOHOoGlucose15-19IsopreneunitHydrophobic portionof this lipidisfarlongerthanthefatty acid tails on membrane phospholipidsPossiblyinahelicalorfoldedconformation
A dolichol sugar that can serve as the donor in glycosyltransferase rxns on the luminal (腔的) side of the endoplasmic reticulum (内质网) membrane Hydrophobic portion of this lipid is far longer than the fatty acid tails on membrane phospholipids! Possibly in a helical or folded conformation!