Deoxyhypusine synthase is essentially required for the post-translational formation of hypusine, a modification of a specific lysine residue in eukaryotic initiation factor 5A, which appears to be pivotal for cell proliferation. From a human peripheral blood mononuclear cells cDNA library we isolated two independent sequences encoding biologically active deoxyhypusine synthase. DNA sequence analysis revealed a 369 amino acid protein with a molecular mass of 41.055 kDa. This recombinant deoxyhypusine synthase showed significant catalytic activity in synthesis of deoxyhypusine after in vitro transcription and translation as well as upon expression in Escherichia coli. Using a panel of somatic rodent-human cell hybrids we localized the deoxyhypusine synthase gene to human chromosome 19.

Using an oligodeoxynucleotide generated by rapid PCR amplification of 5'-cDNA ends (5'-RACE) as a detection probe, we have isolated a new genomic clone encoding the human eukaryotic initiation factor 5A (eIF-5A), Sequence analysis revealed that the eIF-5A coding region is identical to the corresponding cDNA but interrupted by three introns, In a plasmid shuffle experiment we show functional replacement of the essential homologous gene in Saccharomyces cerevisiae by this human eIF-5A.

A genomic clone encoding the human eukaryotic initiation factor 5A (eIF-5A) was isolated and its entire nucleotide sequence was determined. The whole eIF-5A coding region is not interrupted by introns. The functional eIF-5A gene is highly homologous to the corresponding complementary DNA. One single 1.4-kb transcript thereof is expressed in human cell lines. Furthermore, we also isolated and sequenced two additional eIF-5A-related sequences which are, by expression and sequence analyses, identified as pseudogenes of the functional eIF-5A. The sequence homology between these pseudogenes and the functional eIF-5A is 71 and 87%.