phosphorylation

[motivationG]

Does anyone know how looking at a protein sequence will allow you to guess which specific amino acid is phosphorylated?
Thanks

[00febiva]

Does anyone know how looking at a protein sequence will allow you to guess which specific amino acid is phosphorylated?
Thanks

Only Serine and Theronine in a peptide sequence is usually phosphorylated (and sometime tyrosine as well). But not all Ser/Thr in a sequence are phosphorylated and you can't tell which Ser/Thr are phosphorylated unless if you do some futher biochem tests.

[motivationG]

Only Serine and Theronine in a peptide sequence is usually phosphorylated (and sometime tyrosine as well). But not all Ser/Thr in a sequence are phosphorylated and you can't tell which Ser/Thr are phosphorylated unless if you do some futher biochem tests.

Thanks for your reply
Yeah i know that serine and thereonine are the amino acids that are usually phosphorylated but how do i know which one exacly is phosphorylated from the sequence? and what type of biochemical test would i do?
Thanks

[00febiva]

May be if you radioactively label the phosphate group using P32 and then look to see where the radioactivity is located in the sequence. This will tell you the phosphorlyation sites and therefore which ser/thr the phosphate is located. I think there would be a better way of looking at the location of phosphorlyation, but I dont know...sorry!!

[lech26]

Only Serine and Theronine in a peptide sequence is usually phosphorylated (and sometime tyrosine as well). But not all Ser/Thr in a sequence are phosphorylated and you can't tell which Ser/Thr are phosphorylated unless if you do some futher biochem tests.

Tyrosine can be phosphorlylated as well. Often use mutant studies to see if this affects phosphoylation of the protein and there is always bioinformatics. Most important one however is strucutral biology: NMR and X ray crsytallography will give alot of informatio on the phos sites on a protein.
hope this helps.

[lech26]

Only Serine and Theronine in a peptide sequence is usually phosphorylated (and sometime tyrosine as well). But not all Ser/Thr in a sequence are phosphorylated and you can't tell which Ser/Thr are phosphorylated unless if you do some futher biochem tests.

Sorry just seen you put tyr in brackets! not the best at skim reading lol.

[slhollingshead]

a bioinformatics search to identify sequence motifs may help if you know the identity of the phosphorylated protein and its associated protein kinase, but this only gives putative sites, as only motifs located on the outside of the protein (and therefore accessible to the kinase) will be the only ones modified. Alternatively the quickest and most reliable method would be to use mass spec, as this will identify the exact residue in your sequence which has been modified.