detection of protein phosphorylation using M.S. - (Mar/25/2005 )

Is it possible to detect protein phosphorylation by mass spec using lysate? If the sample has to be enriched before M.S., what will be the best way to do it?

Mass spectrometry should be able to identify the difference in MW of phosphorylated and unphosphorylated protein. MALDI-TOF should be able to distinguish difference of 10Da!

Thanks for the info!
I guess my question is what if I don't know what I am looking at or I want to look at all the molecules along a signaling pathway. Can I load samples from a mixture of many different proteins (after digestion) to m.s. and identify their phosphorylation state? If so, it would be a lot more efficient than other methods like WB, FACS and microarray.

hi
i've done phosphorylation state analysis once, and for analyzing particular protein, i suppose it's better to separate them on gel and after input one by one in the MS. That is what we did...

Thx!