Required for cytochrome c complex (COX) IV assembly and function Protects COX assembly from oxidation-induced degradation, COX being the terminal component of the mitochondrial respiratory chain. Expressed in fibroblasts. In conditions of increased oxidative stress, the protein is stabilized, increasing its mature intramitochondrial form and thereby protecting COX from oxidatively induced degradation. N-terminal mitochondrial targeting sequence is cleaved from the mature protein once in the mitochondrion. In normal conditions, the cytoplasmic precursor protein is rapidly degraded by the ubiquitination-proteasome system (UPS). Oxidative stress induces protein stabilization and import into mitochondria where it protects COX from degradation. The disease is caused by variants affecting the gene represented in this entry. Protein may not fold correctly and may be rapidly degraded. Belongs to the COA8 family. It is uncertain whether Met-1 or Met-14 is the initiator. However, according to some experiments, Met-14 seems to be the initiator. First thought to play a role in the regulation of apoptosis, mediating mitochondria-induced cell death in vascular smooth muscle cells through the release of cytochrome c (COX) from mitochondria and the activation of the caspase cascade (By similarity). However, recent studies show that it is not directly involved in apoptosis regulation but in the protection of COX from oxidatively induced degradation (PubMed:30552096, PubMed:25175347). Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.