eIF5A hypusination UPa:UPA00354 PMID:17213197 Post-translational modification of archaea and eukaryotic translation initiation factor 5A (eIF5A), by covalent binding of hypusine to a lysine residue. Hypusine (N epsilon-(4-amino-2-hydroxybutyl)lysine) is a polyamine-derived amino-acid. The biosynthesis of hypusine occurs posttranslationally by modification of a single lysine residue. Translation initiation factor 5A (eIF5A), highly conserved throughout eukaryotes and some archaea, is the only known cellular protein to contain the unique polyamine-derived amino-acid hypusine. The name hypusine reflects the composition of this amino-acid, a combination of hydroxyputrescine and lysine. The unique feature of the hypusine modification is the strict specificity of the enzymes toward its substrate protein, eIF5A. Hypusine is formed in a novel posttranslational modification that involves two enzymes, deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH). [PMID:16452303; PMID:17476569]. PMID:17476569 PMID:16452303 pathway protein modification protein maturation