Figure 1

Model for the interactions between eIF5B domain IV and Met-tRNA _i in the 80S IC. A) Crystal structure of ct eIF5B domain IV (PDB: 4N3G). The most marked differences to domain IV of aIF5B from the archaeon M. thermoautotrophicum (PDB: 1G7T) (B) are found in the lengths of the β3-β4 hairpin and loop L5 as well as in the arrangement of the two C-terminal α helices. C) Original model for the interactions between domain IV (cyan) and Met-tRNA_i (purple), fitted into the cryo-EM density of the 80S IC (EMD-2422) [25]. D) New model for the interactions between domain IV (blue) and Met-tRNA_i (purple), based on the rigid-body fitting of the crystal structure of domain IV from ct eIF5B. The 3′ CCA-end now forms a direct contact with the surface of domain IV, and α^L5 occupies a position in the major groove of the acceptor stem.