eIF1 Initiation Factor

The structure of the smallest initiation factor was determined through nuclear magnetic resonance spectroscopy (Fletcher et al., 1999). eIF1 is a protein of 113 residues, which forms a single domain consisting of a fold formed from two alpha helices on one side of the protein, with mixed parallel and anti-parallel five-stranded beta sheets. The role of the eIF1, which is initiation site selection, is believed to be carried out by a group of residues within this fold that can form a binding site for other factors in intiation. Several changed surface residues are also believed to facilitate factor relationships through electrostatic interactions (Yoon and Donahue, 1992).

The eIF1 sequence, as with many other initiation factors, is highly conserved between different eukaryotes. The equivalence of differently derived eIF1 factors is exemplified through replacing Saccharomyces cerevisiae eIF1 factor, with human eIF1, in vivo, with the result that there are no alterations in translation initiation efficiency (Cui et al., 1998).