Cytochrome c oxidase subunit 5A, mitochondrial
Function
Component of the cytochrome c oxidase, the last enzyme in the mitochondrial electron transport chain which drives oxidative phosphorylation. The respiratory chain contains 3 multisubunit complexes succinate dehydrogenase (complex II, CII), ubiquinol-cytochrome c oxidoreductase (cytochrome b-c1 complex, complex III, CIII) and cytochrome c oxidase (complex IV, CIV), that cooperate to transfer electrons derived from NADH and succinate to molecular oxygen, creating an electrochemical gradient over the inner membrane that drives transmembrane transport and the ATP synthase. Cytochrome c oxidase is the component of the respiratory chain that catalyzes the reduction of oxygen to water. Electrons originating from reduced cytochrome c in the intermembrane space (IMS) are transferred via the dinuclear copper A center (CU(A)) of subunit 2 and heme A of subunit 1 to the active site in subunit 1, a binuclear center (BNC) formed by heme A3 and copper B (CU(B)). The BNC reduces molecular oxygen to 2 water molecules using 4 electrons from cytochrome c in the IMS and 4 protons from the mitochondrial matrix.
Involvement in disease
Mitochondrial complex IV deficiency, nuclear type 20
MC4DN20
An autosomal recessive mitochondrial disorder with onset in early infancy. MC4DN20 is characterized by pulmonary arterial hypertension, poor feeding, failure to thrive, hypotonia, delayed development, increased serum lactate and metabolic acidosis. Death in infancy occurs due to cardiorespiratory failure. Patient tissues show variably decreased levels and activity of mitochondrial respiratory complex IV.
None
The disease may be caused by variants affecting the gene represented in this entry.
Pathway
Energy metabolism; oxidative phosphorylation.
Post-translational modifications
In response to mitochondrial stress, the precursor protein is ubiquitinated by the SIFI complex in the cytoplasm before mitochondrial import, leading to its degradation (PubMed:38297121). Within the SIFI complex, UBR4 initiates ubiquitin chain that are further elongated or branched by KCMF1 (PubMed:38297121).
Sequence Similarities
Belongs to the cytochrome c oxidase subunit 5A family.
Cellular localization
- Mitochondrion inner membrane
- Peripheral membrane protein
- Matrix side
Alternative names
Cytochrome c oxidase polypeptide Va, COX5A