Figure 6
Eukaryotic initiation factor 2 (eIF2) interactions with initiator tRNA and eIF2B are regulated by post-translational modifications (PTMs) and conformational dynamics. Cartoon representation of eIF2 (α, green; β, yellow; and γ, red), Ser51 is highlighted (orange). Locations of PTMs (phosphorylation and acetylation) are indicated (blue; see also Figure 4b). Interactions stabilised by PTMs are highlighted (blue). GTP-bound eIF2 is highly flexible in solution. After binding of Met-tRNAiMet, the ternary complex adopts a more rigid conformation. The unstructured N-terminus of GTP-bound eIF2β interacts with eIF5. Met-tRNAiMet release from eIF2 and transfer to the ribosome is triggered by GTP hydrolysis. GDP is exchanged by nucleotide exchange factor eIF2B preparing eIF2 for a new round of translation initiation. Nucleotide exchange is inhibited by phosphorylation of Ser51.
