Coiled Coil Helix Coiled Coil Helix Domain Containing Protein 4 (CHCHD4)

CHCHD4, a component of human mitochondria, belongs to a protein family whose members share 6 highly conserved cysteine residues constituting a -CXC-CX(9)C-CX(9)C- motif in the C terminus. The human MIA40 (CHCHD4) protein contains the conserved cysteine motif in the C terminus but lacks the N-terminal transmembrane region and the mitochondrial targeting signal present in yeast Mia40. RT-PCR analysis of human tissues showed ubiquitous expression of CHCHD4, with highest levels in liver, kidney, and brain. Western blot analysis detected a 22-kD band that was most prominent in the liver and kidney, followed by lung, brain, heart, and spleen. Immunofluorescence studies localized CHCHD4 to mitochondria and specifically within the intermembrane space.