These are all responsible for the phosphorylation of the alpha subunit of eIF-2 at serine 51, one of the best-characterized mechanisms for down-regulating protein synthesis in eukaryotes as a part of cellular stress response.[3]
^Berlanga, JJ; Santoyo, J; De Haro, C (October 1999). "Characterization of a mammalian homolog of the GCN2 eukaryotic initiation factor 2alpha kinase". European Journal of Biochemistry. 265 (2): 754–62. doi:10.1046/j.1432-1327.1999.00780.x. PMID10504407.