eIF2:GTP eIF2B subunits complex eIF2:GDP: eIF2B eIF2 activation Pubmed2491852 Pubmed3356695 Reactome Database ID Release 4372722 Reactome, http://www.reactome.org ReactomeREACT_1401 eIF2B is a guanine nucleotide releasing factor that is required to cause GDP release so that a new GTP molecule can bind and activate eIF2, so that it can be reused.