text: In bacteria, three rescue mechanisms are known.
  * The main, universal system involves transfer-messenger RNA (tmRNA) and SmpB. The tRNA first binds to the ribosome like a tRNA, then with SmpB's help shifts into the mRNA position to translate a short peptide ending on a normal stop codon.
  * Alternative ribosome-rescue factor A (ArfA) is an alternative system in E. coli. It recruits RF2.
  * Alternative ribosome-rescue factor B (ArfB) is another alternative from E. coli. It works like a GGQ-release factor itself, releasing the peptide from tRNA. At the same time, it fits into the mRNA tunnel to remove the mRNA.
  In eukaryotes, the main mechanism involves PELO:HBS1L.