What are Polyamines?
- Polyamines are abundant, ubiquitous organic cations in all living and dead organisms.
- There are more than 10 enzymes involved in the metabolism of polyamines.
- They are essential for cell survival and proliferation and many physiological functions.
Discovery of eIF5A
- Hypusine found in bovine brain (1971)
- An 18,000-dalton protein found to contain hypusine (1981)
- The 18,000-dalton protein was found to be eIF-4D (1984)
- eIF-4D was renamed as eIF-5A (1987)
- eIF-5A was named as eIF5A (1996)
Properties of eIF5A
- The only known protein containing hypusine
- The sequence of eIF5A is highly conserved
- An essential protein for cell survival and proliferation
- A small and abundant (0.4-1% of total proteins)
- Hypusine exists in all archae and eukaryotes, but not in eubacteria
- Hypusination occurs shortly after the synthesis of eIF-5A precursor
- Hypusine residue exists only on eIF-5A
- Hypusination is not a reversible reaction
- The most specific polyamine-dependent biochemical reaction in nature
- Hypusine also exists as free amino acid in tissue and body fluid, due to degradation of eIF-5A
eIF-5A is highly conserved
Sequence Alignment of eIF-5A from yeast to human.