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Frataxin

Frataxin is a protein that in humans is encoded by the FXN gene.

Function

Frataxin is localized to the mitochondrion. The function of frataxin is not entirely clear, but it seems to be involved in assembly of iron-sulfur clusters. It has been proposed to act as either an iron chaperone or an iron storage protein. Frataxin mRNA is predominantly expressed in tissues with a high metabolic rate (including liver, kidney, brown fat and heart). Mouse and yeast frataxin homologues contain a potential N-terminal mitochondrial targeting sequence, and human frataxin has been observed to co-localise with a mitochondrial protein. Furthermore, disruption of the yeast gene has been shown to result in mitochondrial dysfunction. Friedreich's ataxia is thus believed to be a mitochondrial disease caused by a mutation in the nuclear genome (specifically, expansion of an intronic GAA triplet repeat in the FXN gene, which encodes the protein frataxin.).

Clinical significance

Reduced expression of frataxin is the cause of Friedreich's ataxia (FRDA), a lethal neurodegenerative disease. The reduction in frataxin gene expression may be attributable from either the silencing of transcription of the frataxin gene because of epigenetic modifications in the chromosomal entity or from the inability of splicing the expanded GAA repeats in the first intron of the pre-mRNA as seen in Bacteria and Human cells or both. The expansion of intronic trinucleotide repeat GAA results in Friedreich's ataxia. This expanded repeat causes R-loop formation, and using a repeat-targeted oligonucleotide to disrupt the R-loop can reactivate frataxin expression.

Animal studies

An overexpression of frataxin in Drosophila has shown an increase in antioxidant capability, resistance to oxidative stress insults and longevity.

Interactions

Frataxin has been shown to biologically interact with the enzyme PMPCB.

References

Further reading

External links

"green air" © 2007 - Ingo Malchow, Webdesign Neustrelitz
This article based upon the http://en.wikipedia.org/wiki/Frataxin, the free encyclopaedia Wikipedia and is licensed under the GNU Free Documentation License.
Further informations available on the list of authors and history: http://en.wikipedia.org/w/index.php?title=Frataxin&action=history
presented by: Ingo Malchow, Mirower Bogen 22, 17235 Neustrelitz, Germany