InterPro domain: IPR036925

Initiation factor 2 (IF-2) is one of the three factors required for the initiation of protein biosynthesis in bacteria [ 1 ]. 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 95kDa that contains a central GTP-binding domain flanked by a highly variable N-terminal domain and a more conserved C-terminal domain. Some members of this group undergo protein self splicing that involves a post-translational excision of the intein followed by peptide ligation.

The function of IF-2 in facilitating the proper binding of initiator methionyl-tRNA to the ribosomal P site appears to be universally conserved [ 2 ].

This entry represents the domain 3 superfamily of IF-2. It consists of a alpha/beta/alpha structure with a core formed by a parallel beta-sheet of 4 strands [ 3 ].

1. Initiation of protein synthesis in bacteria. Microbiol. Mol. Biol. Rev. 69, 101-23
2. Universal conservation in translation initiation revealed by human and archaeal homologs of bacterial translation initiation factor IF2. Proc. Natl. Acad. Sci. U.S.A. 96, 4342-7
3. X-Ray structures of the universal translation initiation factor IF2/eIF5B: conformational changes on GDP and GTP binding. Cell 103, 781-92