Deoxyhypusine synthase is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

that in humans is encoded by the ''DHPS''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

. The unusual amino acid

hypusine Hypusine is an uncommon amino acid found in all eukaryotes and in some archaea, but not in bacteria. The only known proteins containing the hypusine residue is eukaryotic translation initiation factor 5A (eIF-5A) and a similar protein found in ...

is formed posttranslationally and is only found in a single cellular protein, eukaryotic translation initiation factor 5A (

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 eI ...

EIF5A2 Eukaryotic translation initiation factor 5A-2 is a protein that in humans is encoded by the ''EIF5A2'' gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." mean ...

). In the first step of hypusine biosynthesis, deoxyhypusine synthase catalyzes the NAD-dependent transfer of the

butylamine Butylamine may refer to any of several related chemical compounds: * ''n''-Butylamine * ''sec''-Butylamine * ''tert''-Butylamine * Isobutylamine Isobutylamine is an organic chemical compound (specifically, an amine) with the formula (CH3)2CHCH2 ...

moiety of

spermidine Spermidine is a polyamine compound () found in ribosomes and living tissues and having various metabolic functions within organisms. It was originally isolated from semen. Function Spermidine is an aliphatic polyamine. Spermidine synthase (SPDS) ...

to the epsilon-amino group of a specific

lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. It contains an α-amino group (which is in the protonated form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −C ...

residue of the EIF5A precursor protein to form the intermediate deoxyhypusine residue. This gene consists of nine

exons An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequence ...

spanning 6.6 kb. Three transcript variants have been isolated. However, only transcript variant 1 encodes an active protein. The shorter variants may act as modulating factors of DHPS activity.

References

Further reading