eIF2alpha Antibody – Mouse Monoclonal

The translation initiation factor EIF2 catalyzes the first regulated step of protein synthesis initiation, promoting the binding of the initiator tRNA to 40S ribosomal subunits. Binding occurs as a ternary complex of methionyl-tRNA, EIF2, and GTP. EIF2 is composed of 3 nonidentical subunits, the 36-kD EIF2-alpha subunit (EIF2S1), the 38-kD EIF2-beta subunit (EIF2S2; MIM 603908), and the 52-kD EIF2-gamma subunit (EIF2S3; MIM 300161). The rate of formation of the ternary complex is modulated by the phosphorylation state of EIF2-alpha (Ernst et al., 1987 [PubMed 2948954]).[supplied by OMIM, Feb 2010]

eIF2-alpha: 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.

Protein type: RNA-binding; Translation; Translation initiation

Chromosomal Location of Human Ortholog: 14q23.3

Cellular Component: cytosol; eukaryotic translation initiation factor 2 complex; eukaryotic translation initiation factor 2B complex; membrane; polysome; ribosome; stress granule

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; translational initiation; transmembrane transport