Published Online: 15 SEP 2010
Copyright © 2001 John Wiley & Sons, Ltd. All rights reserved.
How to Cite
Merry, T. and Astrautsova, S. 2010. Glycoproteins. eLS.
- Published Online: 15 SEP 2010
Glycoproteins are proteins that contain covalently bound oligosaccharides (glycans). Although there are structural features of N- and O-linked glycans common to all eukaryotes, species-specific glycosylation reactions create a wide diversity of structures. This is particularly relevant to cell surface glycoproteins although intracellular and even nuclear proteins may be glycosylated. The factors controlling glycosylation are complex and include the protein sequence and structure, specificity of relevant transferase enzymes, availability of donor sugars and other environmental factors. These may all interact so it is not surprising that there is great variety in glycosylation even on the same protein. Glycosylation of proteins is important in such areas as development and interaction with pathogens and provides a means of modifying the function of proteins that is not directly dependent on their deoxyribonucleic acid (DNA) template. Interest in the field is growing and advances in analytical technology now make the field accessible to a wider community.
Proteins are frequently modified posttranslationally, the most frequent modification being glycosylation.
Glycosylation may play an important role in protein folding through interaction with the chaperones calnexin and calreticulin.
It has been calculated that as many as 70% of all proteins may be glycosylated.
The glycosylation of a protein may vary extensively depending on the cell in which it is produced which may enable the same protein to function in different ways depending where it is expressed.
On the cell surface, glycoprotein glycans are frequently involved in cell–cell interactions.
Glycosylation of the same protein may change during development or in maturation, for example in cells of the immune system.
Glycosylation differs between species even if they are closely related, for example between great apes and man.
Analysis of glycosylation has progressed in recent years and is now almost a routine procedure.
Particular features of glycosylation may only have functional significance in a particular time and place but can be widely distributed which can make assignment of function to glycan structure difficult.
- N-linked glycosylation;
- O-linked glycosylation;
- posttranslational modifications