glycoproteins
Last reviewed 01/2018
Glycoproteins are molecules made from the combination of proteins and carbohydrates.
The Golgi body is the site of most glycoprotein formation which may be either:
- O-linked glycosylation by addition of carbohydrate chains to serine or threonine amino acid residues
- N-linked glycosylation by addition of carbohydrate chains to asparagine residues
Glycoproteins have a number of functions:
- membrane bound:
- glycocalyx - physical cellular protection
- immune recognition
- targetting of membrane-bound vesicles within the cell
- cell receptors e.g. for LDL and ferritin
- thyroglobulin, the storage form of thyroxine
- extracellular matrix recognition molecules e.g. the integrins
- free:
- immunoglobulins
- extracellular matrix components e.g. fibronectin
- haemoglobin
- synthetic plasminogen activating factor