KEGG   ENZYME: 3.6.5.3Help
Entry
EC 3.6.5.3                  Enzyme                                 

Name
protein-synthesizing GTPase;
elongation factor (EF);
initiation factor (IF);
peptide-release or termination factor
Class
Hydrolases;
Acting on acid anhydrides;
Acting on GTP to facilitate cellular and subcellular movement
BRITE hierarchy
Sysname
GTP phosphohydrolase (mRNA-translation-assisting)
Reaction(IUBMB)
GTP + H2O = GDP + phosphate [RN:R00335]
Reaction(KEGG)
Substrate
GTP [CPD:C00044];
H2O [CPD:C00001]
Product
GDP [CPD:C00035];
phosphate [CPD:C00009]
Comment
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-1alpha (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-1alpha 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.
Reference
1  [PMID:6566615]
  Authors
Kurzchalia TV, Bommer UA, Babkina GT, Karpova GG.
  Title
GTP interacts with the gamma-subunit of eukaryotic initiation factor eIF-2.
  Journal
FEBS. Lett. 175 (1984) 313-6.
  Organism
Rattus norvegicus [GN:rno]
Reference
2  [PMID:8722024]
  Authors
Kisselev LL, Frolova LYu.
  Title
Termination of translation in eukaryotes.
  Journal
Biochem. Cell. Biol. 73 (1995) 1079-86.
  Organism
Homo sapiens [GN:hsa], Xenopus laevis [GN:xla]
Reference
3  [PMID:8985244]
  Authors
Rodnina MV, Savelsbergh A, Katunin VI, Wintermeyer W.
  Title
Hydrolysis of GTP by elongation factor G drives tRNA movement on the ribosome.
  Journal
Nature. 385 (1997) 37-41.
  Organism
Thermus thermophilus, Escherichia coli [GN:eco]
Reference
4  [PMID:9233821]
  Authors
Freistroffer DV, Pavlov MY, MacDougall J, Buckingham RH, Ehrenberg M.
  Title
Release factor RF3 in E.coli accelerates the dissociation of release factors RF1 and RF2 from the ribosome in a GTP-dependent manner.
  Journal
EMBO. J. 16 (1997) 4126-33.
  Organism
Escherichia coli [GN:eco]
Reference
5  [PMID:9838020]
  Authors
Krab IM, Parmeggiani A.
  Title
EF-Tu, a GTPase odyssey.
  Journal
Biochim. Biophys. Acta. 1443 (1998) 1-22.
  Organism
Thermus thermophilus, Thermus aquaticus, Salmonella typhimurium
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 

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