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Frataxin is a protein that in humans is encoded by the FXN gene. 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 modifciations 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.〔(【引用サイトリンク】 url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=2395 )〕 An overexpression of frataxin in ''Drosophila'' has shown an increase in antioxidant capability, resistance to oxidative stress insults and longevity. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Frataxin」の詳細全文を読む スポンサード リンク
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