Figure 1. Stress-induced tiRNA-dependent inhibition of translation initiation.

Stress conditions such as oxidation and amino acid starvation induce internalization of extracellular (secreted) angiogenin. When activated, angiogenin cleaves full-length tRNAs at their anticodon loops to give 5′- and 3′-tiRNA fragments of 30–40 nucleotides. A subset of 5′-tiRNAs (5′-tiRNA^Ala/Cys) that contain an oligo-G motif at the 5′-end cooperates with the translational silencer YB-1 to inhibit translation initiation by recruiting eIF4E/G/A from capped mRNAs or eIF4G/A from uncapped mRNAs.