Asn glycosylation
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Introduction
N-glycosylation is conserved from yeast to humans.
Glycoprotein profiling of N-glycans may be facilitated by DSA-FACE.[1]
Activated core oligosaccharide of dolichol pyrophosphate transfered enbloc to a specific asparigine residue of growing ER & GOLGI-processed proteins within the lumen of the endoplasmic reticulum.
Biochemistry
- Asn glycosylation 1
- enzyme: transferase (cytoplasm)
- substrate: dolichol phosphate (ER) + UDP N-acetylglucosamine (cytoplasm))
- product: dolichol pyrophosphate-GlcNAc (ER) + UMP
- Asn glycosylation 2
- enzyme: transferase
- substrate: dolicholpyrophosphate-GlcNAc + UDP N-acetylglucosamine
- product: dolichol pyrophosphate-[GlcNAc]2 +UDP
- reaction on cytoplasmic face of endoplasmic reticulum (ER)
- Asn glycosylation 3
- enzyme: transferase
- substrate: dolichol pyrophosphate-[GlcNAc]2 + 5 GDP-mannose
- product: dolichol pyrophosphate-[GlcNAc]2-[Man]5 + 5 GDP
- reaction on cytoplasmic face of endoplasmic reticulum (ER)
- Asn glycosylation 4
- substrate: dolichol pyrophosphate-[GlcNAc]2-[Man]5
- product: dolichol pyrophosphate-[GlcNAc]2-[Man]5
- translocation from cytoplasmic face to luminal face of ER
- Asn glycosylation 5
- enzyme: transferase
- substrate: dolichol pyrophosphate-[GlcNAc]2-[Man]5 + 4 dolichol phosphate-Man
- product: dolichol pyrophosphate-[GlcNAc]2-[Man]9 + dolichol phosphate
- reaction on luminal face of endoplasmic reticulum (ER)
- Asn glycosylation 6
- enzyme: transferase
- substrate: dolichol pyrophosphate-[GlcNAc]2-[Man]9 + 3 dolicholphosphate-Glc
- product: dolichol pyrophosphate-[GlcNAc]2-[Man]9-[Glc]3 + 3 dolichol phosphate
- reaction on luminal face of endoplasmic reticulum (ER)
- Asn glycosylation 7
- enzyme: transferase
- substrate: dolichol pyrophosphate-[GlcNAc]2-[Man]9-[Glc]3 + glycoprotein
- product: glycoprotein with core oligosaccharide + dolichol pyrophosphate
- N-glycosylated glycoprotein with core oligosaccharide in endoplasmic reticulum