Dr. K.Y. Chen's Laboratory - Hypusine and eIF5A

What are Polyamines?

1. Polyamines are abundant, ubiquitous organic cations in all living and  dead organisms.
2. There are more than 10 enzymes involved in the metabolism of polyamines.
3. They are essential for cell survival and proliferation and many physiological functions.

Discovery of eIF5A

1. Hypusine found in bovine brain (1971)
2. An 18,000-dalton protein found to contain hypusine (1981)
3. The 18,000-dalton protein was found to be eIF-4D (1984)
4. eIF-4D was renamed as eIF-5A (1987)
5. eIF-5A was named as eIF5A (1996)

Properties of eIF5A

1. The only known protein containing hypusine
2. The sequence of eIF5A is highly conserved
3. An essential protein for cell survival  and proliferation
4. A small and abundant (0.4-1% of total proteins)

Hypusination

1. Hypusine exists in all archae and eukaryotes, but not in eubacteria
2. Hypusination occurs shortly after the synthesis of eIF-5A precursor
3. Hypusine residue exists only on eIF-5A
4. Hypusination is not a reversible reaction
5. The most specific polyamine-dependent biochemical reaction in nature
6. 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.