InterPro domain: IPR036788

Initiation factor 3 (IF-3) (gene infC) is one of the three factors required for the initiation of protein biosynthesis in bacteria. IF-3 is thought to function as a fidelity factor during the assembly of the ternary initiation complex which consist of the 30S ribosomal subunit, the initiator tRNA and the messenger RNA. IF-3 is a basic protein that binds to the 30S ribosomal subunit [ 1 ]. The chloroplast initiation factor IF-3(chl) is a protein that enhances the poly(A,U,G)-dependent binding of the initiator tRNA to chloroplast ribosomal 30s subunits in which the central section is evolutionary related to the sequence of bacterial IF-3 [ 2 ].

The C-terminal domain of IF-3 has a beta-alpha-beta-alpha-beta(2) fold arranged into two layers with mixed sheet and strand 4 antiparallel to the rest.

1. Molecular cloning and sequencing of infC, the gene encoding translation initiation factor IF3, from four enterobacterial species. FEMS Microbiol. Lett. 112, 211-6
2. Isolation and characterization of cDNA clones for chloroplast translational initiation factor-3 from Euglena gracilis. J. Biol. Chem. 269, 9436-44