# Elongation factor

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{{distinguish|Relative elongation}}
{{Redirect2|EF2|EF-2|the tornado intensity rating|Enhanced Fujita scale#Parameters}}
{{more citations needed|date=October 2019}}
{{Short description|Proteins functioning in translation}}
thumb|Ternary complex of EF-Tu (blue), tRNA (red) and GTP (yellow). Taken from {{PDB Molecule of the Month|81|Elongation factors}}, September 2006.

'''Elongation factors''' are a set of proteins that function at the [ribosome](/source/ribosome), during [protein synthesis](/source/protein_synthesis), to facilitate [translational](/source/translation_(genetics)) elongation from the formation of the first to the last [peptide bond](/source/peptide_bond) of a growing [polypeptide](/source/polypeptide). Most common elongation factors in prokaryotes are [EF-Tu](/source/EF-Tu), [EF-Ts](/source/EF-Ts), [EF-G](/source/EF-G).<ref>{{cite encyclopedia |last1=Parker |first1=J. |title=Elongation Factors; Translation |encyclopedia=Encyclopedia of Genetics |date=2001 |pages=610–611 |doi=10.1006/rwgn.2001.0402|isbn=9780122270802 }}</ref> Bacteria and eukaryotes use elongation factors that are largely homologous to each other, but with distinct structures and different research nomenclatures.<ref name=eef1>{{Cite journal|last1=Sasikumar|first1=Arjun N.|last2=Perez|first2=Winder B.|last3=Kinzy|first3=Terri Goss|date=July 2012|title=The Many Roles of the Eukaryotic Elongation Factor 1 Complex|journal=Wiley Interdisciplinary Reviews. RNA|volume=3|issue=4|pages=543–555|doi=10.1002/wrna.1118|issn=1757-7004|pmc=3374885|pmid=22555874}}</ref>

Elongation is the most rapid step in translation.<ref>{{Cite journal|last1=Prabhakar|first1=Arjun|last2=Choi|first2=Junhong|last3=Wang|first3=Jinfan|last4=Petrov|first4=Alexey|last5=Puglisi|first5=Joseph D.|date=July 2017|title=Dynamic basis of fidelity and speed in translation: Coordinated multistep mechanisms of elongation and termination|journal=Protein Science |volume=26|issue=7|pages=1352–1362|doi=10.1002/pro.3190|issn=0961-8368|pmc=5477533|pmid=28480640}}</ref> In [bacteria](/source/bacteria), it proceeds at a rate of 15 to 20 [amino acids](/source/amino_acids) added per second (about 45-60 nucleotides per second).{{citation needed|date=October 2019}} In [eukaryotes](/source/eukaryotes) the rate is about two amino acids per second (about 6 nucleotides read per second).{{citation needed|date=October 2019}} Elongation factors play a role in orchestrating the events of this process, and in ensuring the high accuracy translation at these speeds.{{citation needed|date=October 2019}}

==Nomenclature of homologous EFs==
{|class=wikitable
|+Elongation factors
|-
! Bacterial !! Eukaryotic/Archaeal !! Function
|-
| [EF-Tu](/source/EF-Tu) || [eEF-1A](/source/eEF-1) (α)<ref name=eef1/> || mediates the entry of the aminoacyl [tRNA](/source/tRNA) into a free site of the [ribosome](/source/ribosome).<ref>{{cite journal | vauthors = Weijland A, Harmark K, Cool RH, Anborgh PH, Parmeggiani A | title = Elongation factor Tu: a molecular switch in protein biosynthesis | journal = Molecular Microbiology | volume = 6 | issue = 6 | pages = 683–8 | date = March 1992 | pmid = 1573997 | doi = 10.1111/j.1365-2958.1992.tb01516.x | doi-access = free }}</ref>
|-
| [EF-Ts](/source/EF-Ts) || [eEF-1B](/source/eEF-1) ([β](/source/EEF1B2)[γ](/source/EEF1G))<ref name=eef1/> || serves as the guanine [nucleotide exchange factor](/source/nucleotide_exchange_factor) for EF-Tu, catalyzing the release of GDP from EF-Tu.<ref name=eef1/>
|-
| [EF-G](/source/EF-G) || [eEF-2](/source/eEF-2) || catalyzes the translocation of the tRNA and mRNA down the ribosome at the end of each round of polypeptide elongation. Causes large conformation changes.<ref>{{cite journal |last1=Jørgensen |first1=R |last2=Ortiz |first2=PA |last3=Carr-Schmid |first3=A |last4=Nissen |first4=P |last5=Kinzy |first5=TG |last6=Andersen |first6=GR |title=Two crystal structures demonstrate large conformational changes in the eukaryotic ribosomal translocase. |journal=Nature Structural Biology |date=May 2003 |volume=10 |issue=5 |pages=379–85 |doi=10.1038/nsb923 |pmid=12692531|s2cid=4795260 }}</ref>
|-
| [EF-P](/source/Elongation_factor_P) || [eIF-5A](/source/eIF-5A) || possibly stimulates formation of peptide bonds and resolves stalls.<ref name=pmid24402910>{{cite journal |last1=Rossi |first1=D |last2=Kuroshu |first2=R |last3=Zanelli |first3=CF |last4=Valentini |first4=SR |title=eIF5A and EF-P: two unique translation factors are now traveling the same road. |journal=Wiley Interdisciplinary Reviews. RNA |date=2013 |volume=5 |issue=2 |pages=209–22 |doi=10.1002/wrna.1211 |pmid=24402910|s2cid=25447826 }}</ref>
|-
| [EF-4](/source/EF-4) || (None) || Proofreading
|-
| colspan=3 | <small>Note that EIF5A, the archaeal and eukaryotic homolog to EF-P, was named as an initiation factor but now considered an elongation factor as well.<ref name=pmid24402910/></small>
|}

In addition to their cytoplasmic machinery, eukaryotic mitochondria and plastids have their own translation machinery, each with their own set of bacterial-type elongation factors.<ref>{{cite journal |doi-access=free |last1=Manuell |first1=Andrea L |last2=Quispe |first2=Joel |last3=Mayfield |first3=Stephen P |last4=Petsko |first4=Gregory A |title=Structure of the Chloroplast Ribosome: Novel Domains for Translation Regulation |journal=PLOS Biology |date=7 August 2007 |volume=5 |issue=8 |pages=e209 |doi=10.1371/journal.pbio.0050209|pmid=17683199 |pmc=1939882 }}</ref><ref name=":6">{{Cite journal|author1=G C Atkinson |author2=S L Baldauf | title=Evolution of elongation factor G and the origins of mitochondrial and chloroplast forms| journal=Molecular Biology and Evolution| year=2011| volume=28| issue=3| pages=1281–92| pmid = 21097998| doi=10.1093/molbev/msq316 | doi-access=free}}</ref> In humans, they include [TUFM](/source/TUFM), [TSFM](/source/TSFM), [GFM1](/source/GFM1), [GFM2](/source/GFM2), [GUF1](/source/GUF1); the nominal [release factor](/source/release_factor) [MTRFR](/source/MTRFR) may also play a role in elongation.<ref>{{cite web |title=KEGG DISEASE: Combined oxidative phosphorylation deficiency |url=https://www.genome.jp/dbget-bin/www_bget?ds:H00891 |website=www.genome.jp}}</ref>

In bacteria, [selenocysteinyl-tRNA](/source/selenocysteine) requires a special elongation factor ''SelB'' ({{UniProt|P14081}}) related to EF-Tu. A few homologs are also found in archaea, but the functions are unknown.<ref>{{cite journal |last1=Atkinson |first1=Gemma C |last2=Hauryliuk |first2=Vasili |last3=Tenson |first3=Tanel |title=An ancient family of SelB elongation factor-like proteins with a broad but disjunct distribution across archaea |journal=BMC Evolutionary Biology |date=21 January 2011 |volume=11 |issue=1 |page=22 |doi=10.1186/1471-2148-11-22|pmid=21255425 |pmc=3037878 |doi-access=free }}</ref>

== As a target ==
Elongation factors are targets for the toxins of some pathogens. For instance, ''[Corynebacterium diphtheriae](/source/Corynebacterium_diphtheriae)'' produces [diphtheria toxin](/source/diphtheria_toxin), which alters protein function in the host by inactivating elongation factor (EF-2). This results in the pathology and symptoms associated with [diphtheria](/source/diphtheria).<!--NO EXPLICIT MEDICAL CONTENT WITHOUT SOURCES: [pharyngitis](/source/pharyngitis) and [pseudomembranous inflammation](/source/pseudomembranous_inflammation) in the throat.--> Likewise, ''[Pseudomonas aeruginosa](/source/Pseudomonas_aeruginosa)'' [exotoxin A](/source/exotoxin_A) inactivates EF-2.<ref>{{cite journal | vauthors = Lee H, Iglewski WJ | year = 1984 | title = Cellular ADP-ribosyltransferase with the same mechanism of action as diphtheria toxin and Pseudomonas toxin A | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 81 | pages = 2703&ndash;7  | pmid = 6326138 | doi = 10.1073/pnas.81.9.2703 | issue = 9 | pmc = 345138 | bibcode = 1984PNAS...81.2703L | doi-access = free }}</ref>

== References ==
{{reflist}}

==Further reading==
*Alberts, B. et al. (2002). ''Molecular Biology of the Cell'', 4th ed. New York: Garland Science. {{ISBN|0-8153-3218-1}}.{{page needed|date=October 2019}}
*Berg, J. M. et al. (2002). ''Biochemistry'', 5th ed. New York: W.H. Freeman and Company. {{ISBN|0-7167-3051-0}}.{{page needed|date=October 2019}}
*Singh, B. D. (2002). ''Fundamentals of Genetics'', New Delhi, India: Kalyani Publishers. {{ISBN|81-7663-109-4}}.{{page needed|date=October 2019}}

==External links==
* [https://web.archive.org/web/20121015234642/http://www.nobelprize.org/educational/medicine/dna/a/translation/elongation.html nobelprize.org] Explaining the function of eukaryotic elongation factors
* {{MeshName|Elongation+Factor}}
* {{MeshName|Peptide+Elongation+Factor+G}}
* {{MeshName|Peptide+Elongation+Factor+Tu}}
* {{EC number|3.6.5.3}}

{{GeneticTranslation}}
{{GTPases}}

Category:Protein biosynthesis

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Adapted from the Wikipedia article [Elongation factor](https://en.wikipedia.org/wiki/Elongation_factor) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Elongation_factor?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.