The ribosome recycling factor was discovered in the early 1970s by the work of Akira Kaji and Akikazu Hiroshima at the University of Pennsylvania.[5][6][7][8] 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.
RRF accomplishes the recycling of ribosomes by splitting ribosomes into subunits, thereby releasing the bound mRNA. This also requires the participation of EF-G (GFM2 in humans).[9] Depending on the tRNA, IF1–IF3 may also perform recycling.[10]
The crystal structure of RRF was first determined by X-ray diffraction in 1999.[13] 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.[14] 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.
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Hirashima A, Kaji A (November 1970). "Factor dependent breakdown of polysomes". Biochem. Biophys. Res. Commun. 41 (4): 877–883. doi:10.1016/0006-291X(70)90165-8. PMID4920474.
^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. doi:10.1016/0022-2836(72)90490-1. PMID4553259.
^Hirashima A, Kaji A (October 1972). "Purification and properties of ribosome-releasing factor". Biochemistry. 11 (22): 4037–4044. doi:10.1021/bi00772a005. PMID4563926.