9.B.21 The Frataxin (Frataxin) Family
The human frataxin protein is a mitochondrial protein, synthesized from a nuclearly encoded precursor, that is probably involved in iron homeostasis. It has been suggested to function in iron transport (Larsson and Luft, 1999). It is encoded by the FrdA gene which when defective causes Friedreich's ataxia, an autosomal, recessive, progressive, neurodegenerative disease. The disease in most patients is due to GAA triplet repeat expansions in the first intron of the fratixin gene, but sometimes mutation occurs in the coding region. The protein (210 aas) is homologous to the shorter CyaY protein of E. coli (106 aas) The function of this E. coli protein is unknown, but attempts to demonstrate an involvement in iron homeostasis and sensitivity to oxidants using a knockout mutant were not successful (Li et al, 1999).