mRNA-binding protein involved in translation elongation. Has an important function at the level of mRNA turnover, probably acting downstream of decapping (By similarity). Critical for the efficient synthesis of peptide bonds between consecutive proline residues. Can resolve ribosomal stalling caused by consecutive prolines during translation (PubMed:26082486). Required for cell growth during both bloodstream (BF) and insect procyclic (PF) life cycle stages and for survival of the bloodstream form (PubMed:26082486). Localizes to the cytoplasm in the procyclic insect (PF) life cycle stage. Expressed during both bloodstream (BF) and procyclic insect (PF) life cycle stages. 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. Hypusination is mediated by the consecutive action of deoxyhypusine synthase DHSc and deoxyhypusine hydroxylase DOHH (PubMed:26082486). RNAi-mediated knockdown at the bloodstream life cycle stage causes a growth arrest followed by death. Cells become abnormally round, the number of cells with 1N1K and 2N2K genetic content is decreased whereas the number of cells with more than 2N2K genetic content is increased. RNAi-mediated knockdown at the insect procyclic life cycle stage causes a growth arrest without cell death. Cells become abnormally round and about 40 percent have lost their flagella. The number of cells with 2N1K and 2N2K genetic content is increased whereas the number of cells with 1N1K and 1N2K genetic content is reduced. The number of cells without nuclear DNA (0N1K), known as zoids, is increased. In addition, protein expression levels of formin (Tb927.5.2300) and CAP/Srv2p (Tb10.6k15.1160) are severely reduced. Belongs to the eIF-5A family.