Intact or after e.g. tryptic digestion? What is your source material and sample amounts? If you have the purified protein available in sufficient concentration I would venture that you will always be able to find a way to detect it, but I suspect that is not your case here...

Hi Christof,

* digestion + 5 hour HPLC gradients

* my material is cell culture supernatant (0.5 ml per sample) -> defrosted, storage at -80°C

* you are right, I rather expect not to have high concentration of Wnts.

I just learned for the first time that Wnt is secreted at all :-) (doi:10.1038/ncb2574) so cannot help much further here. However here is an approach to find out: 1) perform a secretome prep, 2) use a targeted MS approach to find out if Wnt can be detected, starting from a few heavy AQUA peptides selected from e.g. PeptideAtlas/SRMAtlas. Using synthetic heavy peptides will help you establish detection limits. The people to ask at TUM would be Bernhard Küster's group in case you have not already done so. Good luck!

@Cristina-Maria, thank you for the paper!

@Christof, thank you.

Dear All, I have already asked one person who is expertise in Wnt signaling and indeed Wnt proteins are challenging when one wants to detect them by MS...