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Information on EC 3.6.5.3 - protein-synthesizing GTPase

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EC Tree
IUBMB Comments
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.
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UNIPROT: P13639
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Word Map
The enzyme appears in viruses and cellular organisms
Synonyms
elongation factor, translation initiation factor, gtpase-activating protein, eif2alpha, eif2b, elongation factor tu, eef1a, ef-1alpha, eukaryotic initiation factor 2, elongation factor g, more
SYNONYM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
eukaryotic elongation factor 2
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translation elongation factor 2
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elongation factor (EF)
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GTP phosphohydrolase
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GTPase
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guanine triphosphatase
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guanosine 5'-triphosphatase
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guanosine triphosphatase
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initiation factor (IF)
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peptide-release or termination factor
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ribosomal GTPase
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
hydrolysis of phosphoric ester
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SYSTEMATIC NAME
IUBMB Comments
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-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.
CAS REGISTRY NUMBER
COMMENTARY hide
9059-32-9
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SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
GTP + H2O
GDP + phosphate
show the reaction diagram
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?
additional information
?
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elongation factor eEF2 catalyzes ribosomal reverse translocation at one mRNA triplet. This process requires a cognate tRNA in the ribosomal E-site and cannot occur spontaneously without eEF2. The efficiency of this reaction depends on the concentrations of eEF2 and cognate tRNAs and increases in the presence of nonhydrolyzable GTP analogues. Deacylated tRNAHis, cognate to the E-site codon, to the POST ribosomal complexes along with eEF2-GTP, causes a shift of the main toeprint peak by 3 nt toward the 5' end of the mRNA. POST ribosomes relocate backwards by three nucleotides in the presence of cognate deacylated tRNA and eEF2. Reverse translocation required up to a 20fold excess of eEF2 over the ribosomal complexes, whereas direct translocation is effective at a 2:1 ratio. Model of eEF2-catalyzed reverse translocation, overview
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
GTP + H2O
GDP + phosphate
show the reaction diagram
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?
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Mg2+
required
additional information
high concentrations of Mg2+ and spermidine doe not induce spontaneous reverse translocation, as has been reported
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
cycloheximide
added to the POST complexes in the presence of eEF2 and deacylated tRNAHis, it blocks the -3 nt shift that supports the reverse translocation model
hygromycin B
the antibiotic effectively inhibits translocation of mRNA and tRNAs on the ribosome in both bacteria and eukaryotes. Hygromycin B blocks the toeprint shift induced by eEF2 and deacylated tRNA
additional information
ADP-ribosylation of eEF2 domain IV blocks reverse translocation activity of eEF2. ADP-ribosylation may directly interrupt the ability of eEF2 to stabilize the intermediate conformation of the tRNA ends during their movement through the SSU in the course of translocation
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
GMP-PCP
non-hydrolyzable or slowly hydrolyzable GTP analogues such as GMP-PCP and GMP-PNP, able to stall elongation factor on the ribosome, increase the efficiency of the reverse translocation reaction
GMP-PNP
non-hydrolyzable or slowly hydrolyzable GTP analogues such as GMP-PCP and GMP-PNP, able to stall elongation factor on the ribosome, increase the efficiency of the reverse translocation reaction
additional information
presence of nonhydrolyzable GTP analogues increases the reverse translocation at mRNA activity of eukaryotic elongation factor eEF2. Reverse translocation requires an excessive concentration of cognate deacylated tRNA
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
37
assay at
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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UniProt
Manually annotated by BRENDA team
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
mutations of the conservative histidine H715 residue located at the tip of domain IV decreases the rate of mRNA translocation. ADP-ribosylation of eEF2 domain IV blocks reverse translocation activity of eEF2. ADP-ribosylation may directly interrupt the ability of eEF2 to stabilize the intermediate conformation of the tRNA ends during their movement through the SSU in the course of translocation
physiological function
the eukaryotic elongation factor eEF2 catalyzes ribosomal reverse translocation at one mRNA triplet. This process requires a cognate tRNA in the ribosomal E-site and cannot occur spontaneously without eEF2. The efficiency of this reaction depends on the concentrations of eEF2 and cognate tRNAs and increases in the presence of nonhydrolyzable GTP analogues. Crucial role of interactions of domain IV of eEF2 with the ribosome for the catalysis of the reverse translocation reaction. eEF2 is able to induce ribosomal translocation in forward and backward directions, highlighting the universal mechanism of tRNA-mRNA movements within the ribosome. During forward translocation, eEF2 binds to the PRE complex, capable of undergoing spontaneous conformational changes, including an intersubunit rotation of the ribosomal subunits. During reverse translocation, eEF2 binds to the POST complex, which has a conformation of unrotated ribosomal subunits because no tRNAs with hybrid acceptor ends are present therein. Reverse translocation requires an excessive concentration of cognate deacylated tRNA
UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION?
EF2_HUMAN
858
0
95338
Swiss-Prot
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
eEF2 in vitro translation by rabbit reticulocyte lysate
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Susorov, D.; Zakharov, N.; Shuvalova, E.; Ivanov, A.; Egorova, T.; Shuvalov, A.; Shatsky, I.N.; Alkalaeva, E.
Eukaryotic translation elongation factor 2 (eEF2) catalyzes reverse translocation of the eukaryotic ribosome
J. Biol. Chem.
293
5220-5229
2018
Homo sapiens (P13639)
Manually annotated by BRENDA team