|PROSITE documentation PDOC00905|
Initiation factor 2 (IF-2) (gene infB)  is one of the three factors required for the initiation of protein biosynthesis in bacteria. IF-2 promotes the GTP-dependent binding of the initiator tRNA to the small subunit of the ribosome. IF-2 is a protein of about 70 to 95 Kd which contains a central GTP-binding domain flanked by a highly variable N-terminal domain and a more conserved C-terminal domain.
Bacterial IF-2 is structurally and functionally related to eukaryotic mitochondrial IF-2 (IF-2(mt))  as well as to algal and plants chloroplast IF-2 (IF-2(chl)). Both IF-2(mt) and IF-2(chl) are encoded by nuclear genes and are produced as precursor proteins with a transit peptide. An exception are red algae where IF-2(chl) is encoded by the plastid genome .
As a signature pattern, we selected a conserved region in the C-terminal section of these proteins.Note:
Proteins belonging to this family also contain a copy of the ATP/GTP- binding motif 'A' (P-loop) (see <PDOC00017>).Last update:
April 2006 / Pattern revised.
PROSITE method (with tools and information) covered by this documentation:
|1||Authors||Laalami S. Sacerdot C. Vachon G. Mortensen K. Sperling-Petersen H.U. Cenatiempo Y. Grunberg-Manago M.|
|Title||Structural and functional domains of E coli initiation factor IF2.|
|2||Authors||Ma L. Spremulli L.L.|
|Title||Cloning and sequence analysis of the human mitochondrial translational initiation factor 2 cDNA.|
|Source||J. Biol. Chem. 270:1859-1865(1995).|
|3||Authors||Kostrzewa M. Zetsche K.|
|Title||Organization of plastid-encoded ATPase genes and flanking regions including homologues of infB and tsf in the thermophilic red alga Galdieria sulphuraria.|
|Source||Plant Mol. Biol. 23:67-76(1993).|