Eukaryotic ribosomal subunits are assembled in the nucleus and exported in a functionally inactive state to the cytoplasm, where they undergo final maturation steps before initiating translation. In the case of pre-40S subunits, these steps involve cleavage of the 20S pre-rRNA to the mature 18S rRNA. Two recent studies have surprisingly revealed that mature 60S subunits, aided by the translation initiation factor eIF5b (known as Fun12 in yeast), bind pre-40S subunits to assess their translation 'potential' before triggering cleavage of 20S pre-rRNA.
- Sabina Schütz
- Vikram Govind Panse
