Ribosome Recycling Factor

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mitochondrial ribosome recycling factor
Symbol MRRF
Entrez 92399
HUGO 7234
OMIM 604602
RefSeq NM_138777
UniProt Q96E11
Other data
Locus Chr. 9 q32-q34.1

Ribosome Recycling Factor (RRF) is a protein found in bacterial cells as well as eukaryotic organelles, specifically mitochondria and chloroplasts. It functions to recycle ribosomes after completion of protein synthesis.


The ribosome recycling factor was discovered in the early 1970s by the work of Akira Kaji and Akikazu Hiroshima at the University of Pennsylvania.[1][2][3][4] Their work described the requirement for two protein factors to release ribosomes from mRNA. These two factors were identified as RRF, an unknown protein until then, and Elongation Factor G (EF-G), a protein already identified and known to function in protein synthesis. RRF was originally called Ribosome Releasing Factor but is now called Ribosome Recycling Factor.


Recent evidence suggests RRF may accomplish the recycling of ribosomes by splitting ribosomes into subunits, thereby releasing the bound mRNA.[5]

Loss of RRF function[edit]

Structure of RRF and Binding to Ribosomes[edit]

The crystal structure of RRF was first determined by X-ray diffraction in 1999.[8] The most striking revelation was that RRF is a near-perfect structural mimic of tRNA, in both size and dimensions. One view of RRF can be seen here.

Despite the tRNA-mimicry, RRF binds to ribosomes quite differently from the way tRNA does.[9] It has been suggested that ribosomes bind proteins (or protein domain) of similar shape and size to tRNA, and this, rather than function, explains the observed structural mimicry.

See also[edit]


  1. ^ Hirashima A, Kaji A (November 1970). "Factor dependent breakdown of polysomes". Biochem. Biophys. Res. Commun. 41 (4): 877–83. PMID 4920474. doi:10.1016/0006-291X(70)90165-8. 
  2. ^ Hirashima A, Kaji A (March 1972). "Factor-dependent release of ribosomes from messenger RNA. Requirement for two heat-stable factors". J. Mol. Biol. 65 (1): 43–58. PMID 4553259. doi:10.1016/0022-2836(72)90490-1. 
  3. ^ Hirashima A, Kaji A (October 1972). "Purification and properties of ribosome-releasing factor". Biochemistry. 11 (22): 4037–44. PMID 4563926. doi:10.1021/bi00772a005. 
  4. ^ Hirashima A, Kaji A (November 1973). "Role of elongation factor G and a protein factor on the release of ribosomes from messenger ribonucleic acid". J. Biol. Chem. 248 (21): 7580–7. PMID 4583357. 
  5. ^ Hirokawa G, Demeshkina N, Iwakura N, Kaji H, Kaji A (March 2006). "The ribosome-recycling step: Consensus or controversy?". Trends Biochem. Sci. 31 (3): 143–9. PMID 16487710. doi:10.1016/j.tibs.2006.01.007. 
  6. ^ Janosi L, Shimizu I, Kaji A (May 1994). "Ribosome recycling factor (ribosome releasing factor) is essential for bacterial growth". Proc. Natl. Acad. Sci. U.S.A. 91 (10): 4249–53. PMC 43762Freely accessible. PMID 8183897. doi:10.1073/pnas.91.10.4249. 
  7. ^ Teyssier E, Hirokawa G, Tretiakova A, Jameson B, Kaji A, Kaji H (July 2003). "Temperature-sensitive mutation in yeast mitochondrial ribosome recycling factor (RRF)". Nucleic Acids Res. 31 (14): 4218–26. PMC 165964Freely accessible. PMID 12853640. doi:10.1093/nar/gkg449. 
  8. ^ Selmer M, Al-Karadaghi S, Hirokawa G, Kaji A, Liljas A (December 1999). "Crystal structure of Thermotoga maritima ribosome recycling factor: a tRNA mimic". Science. 286 (5448): 2349–52. PMID 10600747. doi:10.1126/science.286.5448.2349. 
  9. ^ Agrawal RK, Sharma MR, Kiel MC, et al. (June 2004). "Visualization of ribosome-recycling factor on the Escherichia coli 70S ribosome: functional implications". Proc. Natl. Acad. Sci. U.S.A. 101 (24): 8900–5. PMC 428444Freely accessible. PMID 15178758. doi:10.1073/pnas.0401904101. 

External links[edit]