eIF2alpha, also known as EIF2S1 or EIF2, is a 315 amino acid subunit of the eukaryotic initiation complex that functions to bind tRNA to the 40S ribosomal subunit (in a GTP-dependent manner), thereby initiating translation. In addition, the phosphorylation state of eIF2alpha controls the rate of tRNA translation. When eIF2alpha is not phosphorylated, translation occurs at a normal rate. However, upon phosphorylation by one of several kinases, eIF2alpha is stabilized, thus preventing the GDP/GTP exchange reaction and slowing translation.