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.
History
EC 3.6.5.3 created 2000 as EC 3.6.1.48, transferred 2003 to EC 3.6.5.3
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: 

DBGET integrated database retrieval system