Degradation factor 1, Def1, regulates mRNA translation and decay through Ccr4–Not-dependent ubiquitylation of the ribosome

Model for Def1 recruitment to ribosomes. The model is based on the research by Buschauer et al. (2020). When the ribosome experiences arrest or stalling, Not5 binds to the empty E-site, which in turn recruits the Ccr4–Not complex to the ribosome, leading to the ubiquitylation of eS7a. Def1 then binds to the ubiquitylated eS7a through its CUE domain and brings in RNA decay and translation factors to the ribosome via its C-terminal polyQ-rich domain. This recruitment of translation and mRNA regulators facilitates mRNA decay and the removal of the ribosome (constructed by BioRender # TJ29DH76J8).