Practice question

Bacterial translation initiation factor IF2 is GTPase that delivers initiator fMet-tRNAfMet to 30S P site and promotes joining of 50S subunit. Functional analog in eukaryotes is eIF2, heterotrimeric complex of alpha, beta, gamma subunits where gamma subunit shares sequence homology and G-domain architecture with IF2. eIF2 GTP binds Met-tRNAi forming ternary complex that attaches to 40S subunit with other eIFs. Like IF2, eIF2 hydrolyzes GTP during start codon recognition, and its recycling by eIF2B guanine exchange factor is central regulatory node for stress responses.