FRATAXIN GENE OF FRIEDREICHS-ATAXIA IS TARGETED TO MITOCHONDRIA

Friedreich's ataxia is caused by a triplet repeat expansion in intron 1, a noncoding region of the frataxin gene (X25). We have generated a chimeric gene composed of the frataxin gene fused with the green fluor escent protein (GFP) gene as a reporter. Transfection of the fusion co nstruct into living COS cells revealed that the frataxin-GFP construct localizes to organelles that double-label with 8-(4'-chloromethyl) ,1 1,12,14,15-octahydro-1H,4H,10H-13H-diquinolizino 8H-xanthylium chlorid e (CMXRos), a novel mitochondrial dye. Thus, frataxin appears to be a nuclear-encoded mitochondrial protein.