eIF2B

eIF2B is a protein found in eukaryotes. It is the guanine nucleotide exchange factor for the eukaryotic initiation factor 2 and therefore converts the inactive eIF2-GDP to the active eIF2-GTP. This activation is hindered by phosphorylation of the alpha subunit of eIF2, which leads to a stable eIF2α-P-GDP-eIF2B complex and therefore inhibits translation initiation.