EIF2B is a heteropentameric complex (alpha, beta, gamma, delta, and epsilon subunits) essential for protein synthesis that catalyzes GDP/GTP exchange of its Eukaryotic Initiation Factor 2 substrate (restores GTP bound EIF2). For EIF2 to perform additional rounds of initiation, it must be recycled by GDP/GTP exchange. Thus, EIF2B sustains translation. EIF2B-epsilon contains a putative nucleotide-binding domain that may be involved in nucleotide exchange. EIF2B defects cause VWM. (NCI) [ ]