Purity: > 85% by SDS - PAGE Format: Liquid. 20mM Tris-HCl buffer (pH8.0) containing 10% glycerol 0.1M NaCl . EIF2S1, also known as eIF2 alpha, is the alpha subunit of the translation initiation factor eIF2 complex which catalyzes the first regulated step of protein synthesis initiation, promoting the binding of the initiator tRNA to 40S ribosomal subunits. The phosphorylation state of eIF2S1 controls the rate of tRNA translation. When eIF2 alpha is not phosphorylated, translation occurs at a normal rate. However, upon phosphorylation by one of several kinases, eIF2S1 is stabilized, thus preventing the GDP/GTP exchange reaction and slowing translation. Recombinant human EIF2S1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.