eIF2

eIF2α (eukaryotic translation initiation factor 2 alpha) is a central regulator of translation initiation that controls delivery of initiator methionyl-tRNA to the ribosomal preinitiation complex and thereby governs global protein synthesis rates^[1]. Mechanistically, phosphorylation of eIF2α at Ser51 converts the eIF2 complex into an inhibitor of eIF2B, reducing ternary-complex formation and suppressing general cap-dependent translation while permitting selective translation of stress-responsive transcripts such as ATF4^[1][2][3]. This signaling axis forms the core of the integrated stress response (ISR), in which distinct stress-sensing kinases converge on eIF2α to coordinate cellular adaptation and restoration of proteostasis^[2][4]. Through ISR-dependent translational reprogramming, eIF2α regulates amino acid metabolism, redox balance, autophagy, and survival pathways during environmental and metabolic stress^[2][4][5]. In disease contexts, persistent or dysregulated eIF2α phosphorylation has been linked to neurodegenerative disorders, metabolic dysfunction, and other conditions characterized by chronic cellular stress^[3][6][7]. Compared with the β and γ subunits of the eIF2 complex, eIF2α is uniquely distinguished by its regulatory phosphorylation site and its role as the principal stress-responsive signaling node controlling ISR activation^[2][8]. For experimental applications, small molecules targeting the eIF2α-eIF2B regulatory axis, including ISR-modulating compounds such as ISRIB, are widely used to investigate translational control and stress-response mechanisms in cellular and disease models^[7][9].