The precise role of eIF-5A in protein biosynthesis is not known but it may function as a bimodular protein capable of binding to both RNA and proteins. Regulates cytokinin-mediated root protoxylem specification and represses secifically the expression of AHP6. Regulates the induction of programmed cell death caused by infection with virulent pathogen. Homodimer. Interacts with AHK4 and AHP1. Cytokinin regulates the formation of the AHP1-AHK4-ELF5A-2 complex. Ubiquitous. In roots, expressed mostly inside the stele of the mature zone. Constitutively expressed. Up-regulated at post-transcriptional level by wounding and pathogen infection. Lys-51 undergoes hypusination, a unique post-translational modification that consists in the addition of a butylamino group from spermidine to lysine side chain, leading to the formation of the unusual amino acid hypusine. eIF-5As are the only known proteins to undergo this modification, which is essential for their function. Severe defects in plant growth and development. Delayed dark-induced leaf senescence. Dwarfism, defective sporogenesis and shorter primary roots. Impaired protoxylem development. Belongs to the eIF-5A family.