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Recombinant Glycoprotein Expression
O-Glycan Synthesis and Modification
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O-Glycan Synthesis and Modification
Return to Recombinant Glycoprotein ExpressionIn mammals, there are a several different types of O-glycosylation. These include mucin and nonmucin O-glycans.
Mucin glycoproteins:
- Tend to be heavily O-glycosylated.
- Are found in mucous secretions and as transmembrane glycoproteins on the cell surface.
- Addition of O-glycans on the glycoprotein is initiated in the Golgi apparatus.
- Synthesis starts with the addition of an N-acetylgalactosamine (GalNAc) residue to the OH of either a serine or threonine on the glycoprotein.
- There are 8 O-glycan core structures found in mucins (Table 1).
- The growing glycan chain is extended with the addition of other monosaccharides (1, Fig. 1)
![](/en-us/-/media/nebus/page-images/newsized-brochure-images/glycobiology/l2a_oglycan_synthesis.jpg?rev=f6cf27936ec7410e98151302c18a0977&hash=BAA228302AC824AE19297708D901297E)
O-glycan | Structure |
---|---|
Core 1 or T antigen | ![]() |
Core 2 | ![]() |
Core 3 | ![]() |
Core 4 | ![]() |
![](/en-us/-/media/nebus/page-images/products/glycobiology/o-glycans-keys.png?rev=82a7c4b01b704fcfb268c869abae95a2&hash=FEA82D623445CC53BF7C497188E7CE4F)
Non-mucin glycans are more varied:
- O-fucose and O-glucose residues are:
- transferred to consensus cysteine in certain proteins in the ER
- essential for protein interaction and signal transduction (2)
- O-GlcNAc can modify nuclear and cytosolic proteins. This:
- occurs at serine or threonine residues
- is a highly dynamic modification
- plays an important role in cell signaling
- modulates protein function much like phosphorylation (3, Fig. 2)
- can compete directly with phosphate residues for occupancy of serine or threonine residues on the protein
![](/en-us/-/media/nebus/page-images/newsized-brochure-images/glycobiology/l2a_o_glcnac.jpg?rev=0d8ce92652d2445885af037b8f5d315a&hash=172B39CF751D354B5AFB31B332451A38)
References