40S ribosome remodeling triggers 18S rRNA U-tailing and DIS3L2-dependent decay.

Ribosome remodeling and uridylation trigger DIS3L2-dependent decay of defective 40S ribosomal subunits in mammalian cells.

• Why it matters: Understanding how defective ribosomes are identified and eliminated is crucial for maintaining accurate protein synthesis, yet the mechanisms remain poorly understood.
• What they did: An in vitro reconstitution system demonstrated that the kinase RIOK3 remodels 40S subunits, exposing 18S rRNA's 3' end, which is then uridylated and degraded by DIS3L2, with cleavage amplifying decay.
• The result: This stepwise process defines a mechanistic framework for ribosome surveillance, linking remodeling and RNA tailing to the elimination of defective ribosomes.