Comparison of the crystal structures of S. Typhimurium YrlA (Green, PDB: 6cu1), TYMV TLS (Magenta, PDB: 4p5j) and T. thermophilus tmRNA-SmpB complex (Cyan, PDB: 2czj). (A) The three TLEs share the same overall L-shaped fold. (B) The interactions between TSL and DSL are very similar between YrlA, TLS and tmRNA-SmpB. (C) The interactions between the VL and DSL show large differences but maintain the same architecture in the three TLEs. The VLs are colored in red. The three stacking layers of base triples or base pairs are labeled with numbers 1-3. [The numbering of TYMV TLS and T. thermophilus tmRNA-SmpB complex are based on previous publications (Bessho et al., 2007; Colussi et al., 2014)]