Elongation factor

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EF-Tu with tRNA. Taken from PDB Molecule of the Month Elongation factors, September 2006.

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]

Table of corresponding bacterial and eukaryotic/archael EFs[edit]

Elongation factors
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]