mitochondrial intermembrane space import & assembly protein 40 (coiled-coil-helix-coiled-coil-helix domain-containing protein 4, CHCHD4, MIA40)
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Function
- required for the import & folding of small cysteine- containing proteins (small Tim) in the mitochondrial intermembrane space
- probably acts by forming a redox cycle with GFER/ERV1 that involves a disulfide relay system
- precursor proteins to beimported into the IMS are translocated in their reduced form into the mitochondria
- oxidized form of MIA40 forms a transient intermolecular disulfide bridge with the reduced precursor protein, resulting in oxidation of the precursor protein that now
- contains an intramolecular disulfide bond & is able to undergo folding in the mitochondrial intermembrane space
Structure
- homooligomer
- contains 1 CHCH domain with a conserved twin Cys-X(9)-Cys motif which is required for import & stability of MIA40 in mitochondria (probable)
- forms intrachain disulfide bridges, but exists in different redox states
Compartment
mitochondria intermembrane space
Alternative splicing
named isoforms=2
Expression
expressed in all tissues tested