InterPro domain: IPR004368

This family consists of translation initiation factor IF-1 as found in bacteria and chloroplasts. This protein, about 70 residues in length, consists largely of an S1 RNA binding domain ( IPR003029 ) [ 1 ].

Translation initiation includes a number of interrelated steps preceding the formation of the first peptide bond. In Escherichia coli, the initiation mechanism requires, in addition to mRNA, fMet-tRNA, and ribosomal subunits, the presence of three additional proteins (initiation factors IF1, IF2, and IF3) and at least one GTP molecule. The three initiation factors influence both the kinetics and the stability of ternary complex formation. IF1 is the smallest of the three factors. IF1 enhances the rate of 70S ribosome subunit association and dissociation and the interaction of 30S ribosomal subunit with IF2 and IF3. It stimulates 30S complex formation. In addition, by binding to the A-site of the 30S ribosomal subunit, IF1 may contribute to the fidelity of the selection of the initiation site of the mRNA [ 2 , 3 , 4 , 5 , 6 ].

1. The solution structure of the S1 RNA binding domain: a member of an ancient nucleic acid-binding fold. Cell 88, 235-42
2. The structure of the translational initiation factor IF1 from E.coli contains an oligomer-binding motif. EMBO J. 16, 1436-43
3. RNA chaperone activity of translation initiation factor IF1. Biochimie 88, 1875-82
4. Crystal structure of an initiation factor bound to the 30S ribosomal subunit. Science 291, 498-501
5. Interaction of translation initiation factor IF1 with the E. coli ribosomal A site. J. Mol. Biol. 299, 1-15
6. Position of eukaryotic initiation factor eIF1 on the 40S ribosomal subunit determined by directed hydroxyl radical probing. Genes Dev. 17, 2786-97