Intracellular signalling

[mk_2007]

What post-translational modifications play a role in intracellular signalling?

[thedarkshade]

Would you mind explaining more what you actually mean by your question. Because I find it hard to understand and to be honest I feel I've never heard of the subject before (although I have)!

[Mr Skeptic]

Phosphorylation is one of them.

[CharonY]

Do you want a list? Also, for quite a number of modifications, involvements in intracellular signaling have been proposed, but not conclusively shown.

[Hobbz]

Phosphoylation (That's a big one!), ubiquitinylation, acetylation, glycosylation, biotinylation, oxidation (disulfide bridges).

[mk_2007]

a list would be good thanks. I thought glycosylation was co-translational and not post?

[Hobbz]

http://en.wikipedia.org/wiki/Post-translational_modifications

 

Wikipedia above as an extensive list of post-translational modifications and a number of them would be considered co-translational modifications as you pointed out. Co-translational modifications will be considered post-translational modifications since it is after the synthesis of the pepteide chain. So glycosylation won't affect signal pathways that much since it is a more permanent modification. And in biology there are usually exceptions and I tried to find some browsing through pubmed but was unable to find any example of glycosylation of a protein in the cytosol.

 

So, is this what you were looking for?

[CharonY]

A number of intracellular proteins are glycosylated and the function of the glycosylation are manifold. They can , for instance, be necessary for intracellular trafficking (in eukaryotes, of course). Also, many signal molecules are dependent on correct glycosylation. One can, of course argue whether it is intra- or intracellular signalling (dependent on what step you look at).

A classification is also complicated for glycosylated DNA binding proteins. Technically they are not necessarily signaling molecules, however the glycosylation might affect their binding ability and as such there might be changes in gene expression levels, for instance.

[mk_2007]

ah ok. Thank you I understand. one more thing.... with G-proteins, in G-coupled protein receptors, when the GDP is removed and replaced with GTP, is there a specific name for this process ? and is this an example of post translational modification?