Deoxyhypusine synthase catalyzes the cleavage of the polyamine spermidine and transfer of its 4-aminobutyl moiety to the ε-amino group of one specific lysine residue of the eIF-5A precursor to form deoxyhypusine and 1,3-diaminopropane.
ISR is a common denominator of different types of cellular stresses resulting in activation of at least one of the eIF-2 alpha (EIF2S1).