The eukaryotic initiation factor 5a ( eif-5a ) is one of the most abundant initiation factors in the eukaryote, and it is the only protein in nature that contains a hypusine residue 真核起始因子5a(eif-5a)普遍存在于所有真核細胞內(nèi),是目前發(fā)現(xiàn)唯一一個含有hypusine殘基的蛋白質(zhì)。