Scientists led by Javier Martinez from the Max Perutz Labs, a joint venture of the Medical University of Vienna and the University of Vienna, have identified a unique chemical reaction at the end of RNA molecules for the first time in human cells. This reaction was previously only observed in bacteria and viruses. Tracing its source among thousands of proteins, they discovered that an unexpected culprit, an enzyme called ANGEL2, executes this reaction. ANGEL2 may play a key role in regulating the response to cellular stress, and possibly in the pathogenesis of neurodegenerative and metabolic diseases. The study is published in “Science”.