Prokaryotic release factors

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There are three known prokaryotic release factors involved in the termination of translation. RF1 and RF2 are so called class 1 release factors and RF3 a class 2 release factor.

  • RF1 recognize stop codons UAA and UAG.
  • RF2 recognize stop codons UAA and UGA.
  • RF3 promotes termination by either factor by accelerating dissociation.

The release factors provide the means of termination by having a conformation that mimics that of tRNA molecules. The decoding release factor binds to the A site of the ribosome and directly recognises the stop codon.[1] Once RF1 (or RF2) is bound to the ribosome, the polypeptide is released, and the ribosome and release factors disassemble, thus completing the process of translation.[2]


  1. ^ Brown, CM; Tate, WP (1994). "Direct recognition of mRNA stop signals by Escherichia coli polypeptide chain release factor two". The Journal of Biological Chemistry. 269 (52): 33164–70. PMID 7806547. 
  2. ^ Scarlett, D.-J. G.; McCaughan, KK; Wilson, DN; Tate, WP (2002). "Mapping Functionally Important Motifs SPF and GGQ of the Decoding Release Factor RF2 to the Escherichia coli Ribosome by Hydroxyl Radical Footprinting. IMPLICATIONS FOR MACROMOLECULAR MIMICRY AND STRUCTURAL CHANGES IN RF2". Journal of Biological Chemistry. 278 (17): 15095–15104. doi:10.1074/jbc.M211024200. PMID 12458201.