Question: Is there any method to detect whether a protein is at all active (phosphorylated) using a tool such as an antibody that targets all or multiple phosphorylation sites?

Stuart Archer answered on 21 Jun 2013:

That’s a really nice, technical question there 🙂

There are a large number of antibodies that are commercially available now that bind to phosphorylated proteins that can be used to measure the quantity and sites of phosphorylation. The analytical techniques used to detect these changes are really difficult however, and it often results in the complete destruction of the protein.

There are some more recent methods which are reversible i.e. they don’t damage the protein, such as fluorescence immunoassays. This is a technique where you attach a fluorescent molecule to an antibody which binds to the phosphorylated sites on the protein. You can then quantify the amount of fluorescence coming off the proteins to assess the amount of phosphorylation that’s occured. You can then reverse the binding with simple chemistry, restoring the protein.