eIF2α (Eukaryotic Translation Initiation Factor 2α Subunit) is a core subunit of the eukaryotic protein translation initiation complex, encoded by the EIF2S1 gene, and acts as a master regulator of global cellular protein translation. Ubiquitously expressed in all eukaryotic cells, eIF2α assembles with eIF2β and eIF2γ to form the eIF2 complex, which binds GTP and initiator methionine tRNA to mediate ribosomal translation initiation and dominate basal cellular protein synthesis. As a central regulatory node of cellular stress responses, eIF2α phosphorylation suppresses global protein translation and reduces intracellular synthetic burden under endoplasmic reticulum stress, oxidative stress and nutrient deprivation, enabling cells to adapt to adverse conditions. Dysregulated eIF2α expression causes translational disorder and stress imbalance, contributing to tumor proliferation, neurodegeneration, metabolic disorders and inflammation.