An in Vivo Tagging Method Reveals that Ras Undergoes Sustained Activation upon Transglutaminase‐Mediated Protein Serotonylation

Don't interrupt! Protein serotonylation has been implicated in living cells, yet its role remains poorly defined because of the lack of characterization tools. We synthesized a serotonin derivative to enable selective tagging of serotonylation and to investigate its effect on Ras; the latter displayed undisrupted interaction with Raf-1 at the Ras binding domain.