Macromolecular mimicry in translation initiation: A model for the initiation factor IF2 on the ribosome

Protein biosynthesis in bacteria is controlled by a number of translation f actors. Recent data based on comparison of sequence and structure data of t ranslation factors have established a novel hypothesis for their interactio n with the ribosome: initiation, elongation, and termination factors may us e a common or partly overlapping binding site on the ribosome in a process of macromolecular mimicry of an A-site-bound tRNA. This paper reviews struc tural knowledge and tRNA macromolecular mimicry involvement of translation initiation factor IF2. Furthermore, a model is proposed for the factor and its interaction with the ribosome during the formation of the translation i nitiation complex.