Elongation factor
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Elongation factors are a set of proteins that function at the ribosome, during protein synthesis, to facilitate translational elongation from formation of the first to the last peptide bond of a growing polypeptide.[citation needed] Bacteria and eukaryotes use elongation factors that are largely homologous to each other, but with distinct structures (and different research nomenclatures).[citation needed]
Elongation is the most rapid step in translation.[citation needed] In bacteria it proceeds at a rate of 15 to 20 amino acids added per second (about 45-60 nucleotides read, per second).[citation needed] In eukaryotes the rate is about two amino acids per second (about 6 nucleotides read, per second).[citation needed] Elongation factors play a role in orchestrating the events of this process, and in ensuring the highly accuracy translation at these speeds.[citation needed]
Contents
Table of corresponding bacterial and eukaryotic/archael EFs[edit]
| Bacterial | Eukaryotic/Archaeal | Function |
|---|---|---|
| EF-Tu | eEF-1 subunit α | mediates the entry of the aminoacyl tRNA into a free site of the ribosome.[citation needed] |
| EF-Ts | eEF-1 subunit βγ | serves as the guanine nucleotide exchange factor for EF-Tu, catalyzing the release of GDP from EF-Tu.[citation needed] |
| EF-G | eEF-2 | catalyzes the translocation of the tRNA and mRNA down the ribosome at the end of each round of polypeptide elongation. Shaped like EF-Tu plus tRNA.[citation needed] |
| EF-P | EIF5A | stimulates peptide formation by catalyzing the first synthesis step between the first amino acid (N-formylmethionine/methionine) and the second amino acid.[citation needed] |
| Note that EIF5A, the archaeal and eukaryotic homolog to EF-P, is instead considered an initiation factor.[citation needed] | ||
In addition to their cytoplasmic machinery, eukaryotic mitochrondria and plastids have their own translation machineries, each with their own set of bacterial-type elongation factors.[citation needed] In humans, they include TUFM, TSFM, GFM1, GFM2.[citation needed]
As a target[edit]
Elongation factors are targets for the toxins of some pathogens.[citation needed] For instance, Corynebacterium diphtheriae produces its toxin, which alters protein function in the host by inactivating elongation factor (EF-2).[citation needed] This results in the pathology and symptoms associated with C. diphtheriae infection.[citation needed] Likewise, Pseudomonas aeruginosa exotoxin A inactivates EF-2.[verification needed][citation needed]
References[edit]
Further reading[edit]
- Alberts, B. et al. (2002). Molecular Biology of the Cell, 4th ed. New York: Garland Science. ISBN 0-8153-3218-1.[page needed]
- Berg, J. M. et al. (2002). Biochemistry, 5th ed. New York: W.H. Freeman and Company. ISBN 0-7167-3051-0.[page needed]
- Singh, B. D. (2002). Fundamentals of Genetics, New Delhi, India: Kalyani Publishers. ISBN 81-7663-109-4.[page needed]
External links[edit]
- nobelprize.org Explaining the function of eukaryotic elongation factors
- Elongation+Factor at the US National Library of Medicine Medical Subject Headings (MeSH)
- Peptide+Elongation+Factor+G at the US National Library of Medicine Medical Subject Headings (MeSH)
- Peptide+Elongation+Factor+Tu at the US National Library of Medicine Medical Subject Headings (MeSH)
- EC 3.6.5.3
