The function of EIF2B5 (eukaryotic translation initiation factor 2B subunit epsilon, Ensembl gene identifier ENSG00000145191) is as follows. Acts as a component of the translation initiation factor 2B (eIF2B) complex, which catalyzes the exchange of GDP for GTP on eukaryotic initiation factor 2 (eIF2) gamma subunit (PubMed:25858979, PubMed:27023709, PubMed:31048492). Its guanine nucleotide exchange factor activity is repressed when bound to eIF2 complex phosphorylated on the alpha subunit, thereby limiting the amount of methionyl- initiator methionine tRNA available to the ribosome and consequently global translation is repressed (PubMed:25858979, PubMed:31048492). {ECO:0000269|PubMed:25858979, ECO:0000269|PubMed:27023709, ECO:0000269|PubMed:31048492}.