Figure 5

Conformational rearrangement of Met-tRNA _i on the initiation complex. eIF5B stabilizes the initiator tRNA (purple) in a non-canonical P/I conformation [25] with the 3′ CCA-end outside of the PTC. Upon GTP hydrolysis in eIF5B and the release of the 3′ CCA-end from its contacts to domain IV, the initiator tRNA rearranges into the canonical P site conformation, involving a 20 Å repositioning of the 3′ end into the PTC.