Overlapping regions of Caf20 mediate its interactions with the mRNA-5′cap-binding protein eIF4E and with ribosomes

Abstract By interacting with the mRNA 5′ cap, translation initiation factor eIF4E plays a critical role in selecting mRNAs for protein synthesis eukaryotic cells. Caf20 is member of family proteins found across eukaryotes termed 4E-BPs, which compete eIF4G interaction eIF4E. independently interacts ribosomes. Thus, modulates selection process via poorly understood mechanisms. Here we performed unbiased mutagenesis to characterise regions are important and binding entirely dependent on canonical motif shared other 4E-BPs. However, ribosomes weakened by mutations throughout protein, suggesting an extended interface that partially overlaps eIF4E-interaction region. using chemical crosslinking, identify potential ribosome region surface spans both small large subunits close known site eIF3. The function remains unclear.