Eukaryotic translation initiation factor 5A-1 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respon ...
that in humans is encoded by the ''EIF5A''
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 b ...
.
It is the only known protein to contain 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 a ...
'N''ε-(4-amino-2-hydroxybutyl)-lysine which is synthesized on eIF5A at a specific lysine residue from the polyamine
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 ...
by two catalytic steps.
is the bacterial
homolog
In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the Bat wing development, wings of bats and Ori ...
of eIF5A, which is 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
Elongation factors are a set of proteins that function at the ribosome, during protein synthesis, to facilitate translational elongation from the formation of the first to the last peptide bond of a growing polypeptide. Most common elongatio ...
despite the "
initiation factor Initiation factors are proteins that bind to the small subunit of the ribosome during the initiation of translation, a part of protein biosynthesis.
Initiation factors can interact with repressors to slow down or prevent translation. They have th ...
" name originally assigned.
Clinical relevance
Germline deleterious heterozygous ''EIF5A'' variants caus
Faundes-Banka syndrome This rare human disorder is characterized by variable combinations of developmental delay, microcephaly, micrognathia and dysmorphic features.
References
Further reading
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Rare diseases