EIF5A

Eukaryotic translation initiation factor 5A-1 is a protein that in humans is encoded by the "EIF5A" gene.
It is the only known protein to contain the unusual amino acid hypusine [N (ε)- (4-amino-2-hydroxybutyl)-lysine], which is synthesized on eIF5A at a specific lysine residue from the polyamine spermidine by two catalytic steps.
EF-P is the prokaryotic homolog of eIF5A, which is also modified post-translationally in a similar but distinct way. Both proteins are believed to catalyze peptide bond formation and help resolve ribosomal stalls, making them elongation factors.