Structure of the heme-regulated eukaryotic initiation factor 2 alpha kinase. End group analysis and phosphoaminoacid...

The Mr 80,000 subunit of the inhibitor of protein synthesis that is activated in heme deficiency was purified from SDS gels. Radiolabelled reagents were used to determine the end terminal residues: the N-terminal residue was found to be only glutamine, and the C-terminal residue only valine. Phosphoaminoacids determination revealed both phosphoserine and phosphothreonine.