Elongation factors are a set of proteins that function at the
ribosome, during
protein synthesis, to facilitate
translational elongation from the formation of the first to the last
peptide bond of a growing
polypeptide. Most common elongation factors in prokaryotes are
EF-Tu,
EF-Ts,
EF-G.[1] Bacteria and eukaryotes use elongation factors that are largely homologous to each other, but with distinct structures and different research nomenclatures.[2]
Elongation is the most rapid step in translation.[3] In
bacteria, it proceeds at a rate of 15 to 20
amino acids added per second (about 45-60 nucleotides 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 high accuracy translation at these speeds.[citation needed]
catalyzes the translocation of the tRNA and mRNA down the ribosome at the end of each round of polypeptide elongation. Causes large conformation changes.[5]
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.[6]
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.[7][8] In humans, they include
TUFM,
TSFM,
GFM1,
GFM2,
GUF1; the nominal
release factorMTRFR may also play a role in elongation.[9]
In bacteria,
selenocysteinyl-tRNA requires a special elongation factor SelB (P14081) related to EF-Tu. A few homologs are also found in archaea, but the functions are unknown.[10]
^Jørgensen, R; Ortiz, PA; Carr-Schmid, A; Nissen, P; Kinzy, TG; Andersen, GR (May 2003). "Two crystal structures demonstrate large conformational changes in the eukaryotic ribosomal translocase". Nature Structural Biology. 10 (5): 379–85.
doi:
10.1038/nsb923.
PMID12692531.
S2CID4795260.
^
abRossi, D; Kuroshu, R; Zanelli, CF; Valentini, SR (2013). "eIF5A and EF-P: two unique translation factors are now traveling the same road". Wiley Interdisciplinary Reviews. RNA. 5 (2): 209–22.
doi:
10.1002/wrna.1211.
PMID24402910.
S2CID25447826.