For decades it has been an open question in the ubiquitin research field how proteins are labeled as being defective or unneeded. In a recent study Brenda Schulman, Director at the Max Planck Institute (MPI) of Biochemistry, and Gary Kleiger, Chair of Chemistry and Biochemistry Department at University of Las Vegas Nevada, together with their teams were able to visualize this precise mechanism, catalyzed by the Cullin-RING Ligase E3s, for the first time.