a translation initiation factor that 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 preinitiation 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. Phosphorylated by at least 4 kinases: PERK, GCN2, HRI and PKR. Phosphorylation 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. Upregulated in some thyroid cancers and bronchiolo-alveolar adenocarcinomas; aberrant phosphorylation correlates with Alzheimer disease and Epstein-Barr virus infections. Note: This description may include information from UniProtKB.
Protein type: RNA-binding; Translation; Translation initiation
Molecular Function: protein binding; ribosome binding; translation initiation factor activity
Biological Process: cellular response to amino acid starvation; negative regulation of translation initiation in response to stress; positive regulation of defense response to virus by host; translational initiation; transmembrane transport