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ENZYME entry: EC 3.6.5.3

Accepted Name
protein-synthesizing GTPase.
Alternative Name(s)
elongation factor (EF).
initiation factor (IF).
peptide-release factor (RF).
peptide-release or termination factor.
Reaction catalysed
GTP + H2O <=> GDP + H(+) + phosphate
Comment(s)
  • 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 hydrolyzes it in prokaryotes.
  • In eukaryotes, it is eIF-2 (150 kDa) that binds GTP.
  • In the elongation phase, the GTP-hydrolyzing 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 catalyze binding of aminoacyl-tRNA to the ribosomal A-site, while EF-G and EF-2 catalyze 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.
  • Formerly EC 3.6.1.48.
Cross-references
BRENDA3.6.5.3
EC2PDB3.6.5.3
ExplorEnz3.6.5.3
PRIAM enzyme-specific profiles3.6.5.3
KEGG Ligand Database for Enzyme Nomenclature3.6.5.3
IUBMB Enzyme Nomenclature3.6.5.3
IntEnz3.6.5.3
MEDLINEFind literature relating to 3.6.5.3
MetaCyc3.6.5.3
Rhea expert-curated reactions3.6.5.3
UniProtKB/Swiss-Prot
Q2VIR3, IF2GL_HUMAN;  Q9Y9C1, IF2G_AERPE;  O29663, IF2G_ARCFU;  
Q2KHU8, IF2G_BOVIN;  Q5ZMS3, IF2G_CHICK;  J9VR81, IF2G_CRYNH;  
F1QGW6, IF2G_DANRE;  Q54XD8, IF2G_DICDI;  Q24208, IF2G_DROME;  
O96719, IF2G_ENCCU;  B9LSM6, IF2G_HALLT;  Q5UYS2, IF2G_HALMA;  
B0R6Y7, IF2G_HALS3;  Q9HNK9, IF2G_HALSA;  Q18KI6, IF2G_HALWD;  
P41091, IF2G_HUMAN;  A6UTL4, IF2G_META3;  Q8TJT7, IF2G_METAC;  
Q58657, IF2G_METJA;  Q8TVE5, IF2G_METKA;  A4FWW9, IF2G_METM5;  
A9AAA4, IF2G_METM6;  A6VGE8, IF2G_METM7;  Q8PZA0, IF2G_METMA;  
Q6LXY6, IF2G_METMP;  O26361, IF2G_METTH;  A6UPK8, IF2G_METVS;  
Q9Z0N1, IF2G_MOUSE;  Q3IMM5, IF2G_NATPD;  Q5R797, IF2G_PONAB;  
Q9V1G0, IF2G_PYRAB;  Q8U082, IF2G_PYRFU;  O59410, IF2G_PYRHO;  
P81795, IF2G_RAT;  Q980A5, IF2G_SACS2;  Q09130, IF2G_SCHPO;  
O36041, IF2G_SPIVO;  Q975N8, IF2G_SULTO;  Q9HLA7, IF2G_THEAC;  
Q5JDL3, IF2G_THEKO;  B6YW69, IF2G_THEON;  Q978W8, IF2G_THEVO;  
P32481, IF2G_YEAST;  Q9Z0N2, IF2H_MOUSE;  C9WPN6, IF2H_RAT;  
G0S8G9, IF2P_CHATD;  Q54XP6, IF2P_DICDI;  O60841, IF2P_HUMAN;  
Q05D44, IF2P_MOUSE;  Q5RDE1, IF2P_PONAB;  B2GUV7, IF2P_RAT;  
Q10251, IF2P_SCHPO;  P39730, IF2P_YEAST;  

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