3 Questions
What is the difference between N-linked and O-linked glycosylation?
N-linked glycosylation adds sugars one at a time to the polypeptide chain, while O-linked glycosylation adds a whole bunch of sugars.
Which molecule is responsible for transferring sugars from the cytosol to the ER lumen?
Dolichol phosphate
What is the role of the protein that can flip the dolichol phosphate?
To transfer sugars from the cytosol to the ER lumen
Study Notes
Glycosylation Types
- N-linked glycosylation: occurs in the endoplasmic reticulum (ER) and involves the attachment of a carbohydrate molecule to an asparagine residue in a protein
- O-linked glycosylation: occurs in the Golgi apparatus and involves the attachment of a carbohydrate molecule to a serine or threonine residue in a protein
Glycosylation Process
- The molecule responsible for transferring sugars from the cytosol to the ER lumen is oligosaccharyltransferase (OST)
- Oligosaccharyltransferase (OST) transfers a pre-assembled oligosaccharide from dolichol phosphate to the asparagine residue of a protein
Dolichol Phosphate Function
- The protein that can flip dolichol phosphate is called flippase
- Flippase is responsible for flipping dolichol phosphate from the cytosolic side to the luminal side of the ER, allowing the transfer of sugars to occur
Test your knowledge on dolichol phosphate and its role in protein glycosylation. Explore the process of sugar transfer from the cytosol to the ER lumen and learn about N-linked glycosylation.
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