Figure 6.
Representative examples of modulation of translation by tRFs. (A) Inhibition of translation by human l-tRF (Ala), via a G-quadruplex structure (Gq), by displacement of eIF4G/A and interaction with YB-1. (B) In human cells and this work in Arabidopsis shows that s-tRFs can associate with active polyribosomes. The two residues G18 and G19 (GG) are essential. Also, an interaction between the MultiSynthetases Complex (MSC) and tRFs have been characterized in humans. Note that in human cells, while global repression of translation has been observed [19], the protein synthesis of a specific set of mRNAs (coding for ribosomal and RNA-binding proteins) is, by contrast, stimulated [19]. (C) In the archaea H. volcanii, s-tRFs bind to the small ribosomal subunit and compete with mRNA for ribosome binding. (D) In the yeast S. cerevisiae, l-tRFs directly interact with the small ribosomal subunit and with aminoacyl-tRNA synthetases associated with ribosomes, thus impairing tRNA aminoacylation. (E) The tRNAThr 3ʹ half (depicted in green) stimulates protein synthesis in the protozoan T. brucei, by interacting with ribosomes.