<p>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 basicprotein that binds to the 30S ribosomal subunit [<cite idref="PUB00001732"/>]. 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 ribosomal30s subunits in which the central section is evolutionary related to the sequence of bacterial IF-3 [<cite idref="PUB00002896"/>]. </p>