EC - Protein-synthesizing GTPase

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IntEnz Enzyme Nomenclature


Accepted name:
protein-synthesizing GTPase
Other names:
elongation factor (EF)
initiation factor (IF)
peptide-release or termination factor
Systematic name:
GTP phosphohydrolase (mRNA-translation-assisting)



This enzyme comprises a family of proteins involved in prokaryotic as well as eukaryotic protein synthesis. In the initiation factor complex, it is IF-2b (98 kDa) that binds GTP and subsequently hydrolyses it in prokaryotes. In eukaryotes, it is eIF-2 (150 kDa) that binds GTP. In the elongation phase, the GTP-hydrolysing proteins are the EF-Tu polypeptide of the prokaryotic transfer factor (43 kDa), the eukaryotic elongation factor EF-1α (53 kDa), the prokaryotic EF-G (77 kDa), the eukaryotic EF-2 (70-110 kDa) and the signal recognition particle that play a role in endoplasmic reticulum protein synthesis (325 kDa). EF-Tu and EF-1α catalyse binding of aminoacyl-tRNA to the ribosomal A-site, while EF-G and EF-2 catalyse the translocation of peptidyl-tRNA from the A-site to the P-site. GTPase activity is also involved in polypeptide release from the ribosome with the aid of the pRFs and eRFs.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00273 , PROSITE:PDOC00905 , PROSITE:PDOC00970
Structural data: CSA , EC2PDB
UniProtKB/Swiss-Prot: (55) [show] [UniProt]


  1. Kurzchalia, T.V., Bommer, U.A., Babkina, G.T. and Karpova, G.G.
    GTP interacts with the γ-subunit of eukaryotic initiation factor EIF-2.
    FEBS Lett. 175 : 313-316 (1984). [PMID: 6566615]
  2. Kisselev, L.L. and Frolova, L.Yu.
    Termination of translation in eukaryotes.
    Biochem. Cell Biol. 73 : 1079-1086 (1995). [PMID: 8722024]
  3. Rodnina, M.V., Savelsberg, A., Katunin, V.I. and Wintermeyer, W.
    Hydrolysis of GTP by elongation factor G drives tRNA movement on the ribosome.
    Nature 385 : 37-41 (1997). [PMID: 8985244]
  4. Freistroffer, D.V., Pavlov, M.Y., MacDougall, J., Buckingham, R.H. and Ehrenberg, M.
    Release factor RF3 in E. coli accelerates the dissociation of release factors RF1 and RF2 from the ribosome in a GTP-dependent manner.
    EMBO J. 16 : 4126-4133 (1997). [PMID: 9233821]
  5. Krab, I.M. and Parmeggiani, A.
    EF-Tu, a GTPase odyssey.
    Biochim. Biophys. Acta 1443 : 1-22 (1998). [PMID: 9838020]

[EC created 2000 as EC, transferred 2003 to EC]