Figure 1.

The activation of the RQC machinery results in stalled ribosome resolution and degradation of aberrant nascent chains. After scanning the arrested ribosomes, (1) the RQC complex induces the dissociation of the small and large ribosomal subunit, followed by (2) the hydrolysis of the tRNA from the nascent chain, the recycling of the translation machinery and, finally, (3) the degradation through the 28S proteasome of the aberrant nascent chains produced by stalled ribosomes. All these steps are achieved via a fine-tuned regulation of all the molecular players involved, and also thanks to the redundant action of specific proteins, which assures a complete and correct control over the possible errors of the translation process (see text for details).