frataxin; Friedreich ataxia protein (FXN, FRDA, X25)

Function

• regulation of mitochondrial iron metabolism (putative)
  • may regulate iron efflux
  • may regulate biogenesis of iron-sulfur clusters
• anti-apoptotic protein
• prevents mitochondrial damage & reactive oxygen species (ROS) production
• processed in 2 steps by mitochondrial processing peptidase (MPP)
• MPP first cleaves the precursor to intermediate form & subsequently converts the intermediate to mature size protein
• 2 forms exist, frataxin(56-210) & frataxin(81-210) which is the main form of mature frataxin
• interacts with LYRM4 & HSPA9

Structure

• monomer
• belongs to the frataxin family

Compartment

• mitochondria
• mitochondrial & extramitochondrial

Alternative splicing

• named isoforms=2
• frataxin(56-210) not highly expressed; may be artifactual

Expression

• frataxin(81-210) is expressed in the heart, peripheral blood lymphocytes & dermal fibroblasts
• expressed in high levels in:
  • dentate nucleus
  • dorsal root ganglion (DRG)
  • sensory fibers of peripheral nerves
  • pyramidal tract
  • spinocerebellar tract
  • posterior columns of spinal cord

Pathology

• defects in FXN are the cause of Friedreich ataxia

Laboratory

• FXN gene GAA repeats
• frataxin in blood
• frataxin in dried blood spot

More general terms

• mitochondrial protein

Additional terms

• Friedreich ataxia

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=2395
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:2395
• OMIM: https://mirror.omim.org/entry/229300
• OMIM: https://mirror.omim.org/entry/606829
• UniProt: http://www.uniprot.org/uniprot/Q16595.html