eIF5A isoforms 1 and 2 are hypusinated via a two-step enzymatic process that requires Spermidine as the donor of 4-aminobutyl moiety and the enzymes DHPS and DOHH. Hypusination activates the protein which takes part in start codon selection, translation elongation and termination. Non-hypusinated eIF5A can be acetylated by PCAF. Acetylated eIF5A translocated to the nucleus where it becomes inactivated. Deacetylases can reverse the modification and lead to translocation of the protein back to the cytoplasm. All enzymes that participate in eIF5A post-translational modifications can be deactivated via small molecule inhibitors. Apart from the cytoplasm and the nucleus eIF5A has been found to localise in mitochondria, the ER and stress granules under oxidative stress conditions. In each compartment eIF5A has a different functional role.