Start codon selection is a key step in translation initiation as it sets the reading frame for decoding. Two eukaryotic initiation factors, eIF1 and eIF1A, are key actors in this process. Recent work has elucidated many details of the mechanisms these factors use to control start site selection. eIF1 prevents the irreversible GTP hydrolysis that commits the ribosome to initiation at a particular codon. eIF1A both promotes and inhibits commitment through the competing influences of its two unstructured termini. Both factors perform their tasks through a variety of interactions with other components of the initiation machinery, in many cases mediated by the unstructured regions of the two proteins.
Mitchell, Sarah F, and Jon R Lorsch. “Should I stay or should I go? Eukaryotic translation initiation factors 1 and 1A control start codon recognition.” The Journal of biological chemistry vol. 283,41 (2008): 27345-9. doi:10.1074/jbc.R800031200