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. Involved in supporting growth and plays a regulatory role in the response to sub-lethal osmotic and nutrient stress. Expressed in the vascular tissues of roots, stems and leaves. Localized in phloem companion cells rather than sieve-tube members. Not expressed in xylem or procambium. Detected in root tips and in the chalazal tissue of fertilized ovules. Up-regulated at post-transcriptional level by iron deficiency. Lys-52 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. No visible phenotype, but presence of extra root protoxylem cell files. Belongs to the eIF-5A family.