Functions in the early steps of protein synthesis by forming a ternary complex with GTP and initiator tRNA. This complex binds to a 40S ribosomal subunit, followed by mRNA binding to form a 43S pre-initiation complex. Junction of the 60S ribosomal subunit to form the 80S initiation complex is preceded by hydrolysis of the GTP bound to eIF-2 and release of an eIF-2-GDP binary complex. In order for eIF-2 to recycle and catalyze another round of initiation, the GDP bound to eIF-2 must exchange with GTP by way of a reaction catalyzed by eIF-2B. EIF2S1/eIF-2-alpha is a key component of the integrated stress response (ISR), required for adaptation to various stress: phosphorylation by metabolic-stress sensing protein kinases in response to stress converts EIF2S1/eIF-2-alpha in a global protein synthesis inhibitor, leading to a attenuation of cap-dependent translation, while concomitantly initiating the preferential translation of ISR-specific mRNAs, such as the transcriptional activators ATF4 and QRICH1. Activity is regulated by phosphorylation at Ser-49 and Ser-52, which stabilizes the eIF-2/GDP/eIF-2B complex and prevents the eIF-2B-mediated exchange of GDP for GTP, thereby preventing the formation of the 43S pre-initiation complex (PIC). This results in the global attenuation of 5' cap-dependent protein synthesis and concomitant translation of ISR-specific mRNAs that contain a short upstream open reading frame (uORF) in their 5' UTR. Heterotrimer composed of an alpha, a beta and a gamma chain. Phosphorylation at Ser-49 and Ser-52 stabilizes the eIF-2/GDP/eIF-2B complex and prevents GDP/GTP exchange reaction, thus impairing the recycling of eIF-2 between successive rounds of initiation and leading to global inhibition of translation, while concomitantly initiating the preferential translation of integrated stress response (ISR)-specific mRNAs. Belongs to the eIF-2-alpha family. Truncated C-terminus.