Ubiquitin-a beacon for all during quality control on the ribosome.

Ribosome stalling triggers no-go decay (NGD) and ribosome-associated quality control (RQC) pathways to rapidly degrade the aberrant mRNA and the incomplete nascent peptide, respectively. Two recent studies in yeast and mammalian systems reveal the importance of stalling-induced ribosomal protein ubiquitination by Hel2/ZNF598 for both NGD and RQC The studies also structurally explain how collided ribosomes generate a unique interface not present in monosomes, which can be recognized by Hel2/ZNF598 ubiquitin ligases.