InterPro domain: IPR044123

EIF2B is the guanine nucleotide exchange factor for protein synthesis initiation factor 2 (eIF2). EIF2B is a complex multimeric protein consisting of five subunits named alpha, beta, gamma, delta and epsilon. The epsilon and gamma subunits are sequence similar and both are essential in yeast. Epsilon appears to be the catalytically active subunit, with gamma enhancing its activity [ 1 ]. The C-terminal domain of the eIF2B epsilon subunit contains bipartite motifs rich in acidic and aromatic residues. It is required for both catalytic activity and interaction with eIF2. The structure of the domain resembles that of a set of concatenated HEAT repeats [ 2 , 3 ].

1. Identification of intersubunit domain interactions within eukaryotic initiation factor (eIF) 2B, the nucleotide exchange factor for translation initiation. J. Biol. Chem. 287, 8275-85
2. Identification of domains and residues within the epsilon subunit of eukaryotic translation initiation factor 2B (eIF2Bepsilon) required for guanine nucleotide exchange reveals a novel activation function promoted by eIF2B complex formation. Mol. Cell. Biol. 20, 3965-76
3. Conserved bipartite motifs in yeast eIF5 and eIF2Bepsilon, GTPase-activating and GDP-GTP exchange factors in translation initiation, mediate binding to their common substrate eIF2. EMBO J. 18, 1673-88