Copper metallochaperone essential for the synthesis and maturation of cytochrome c oxidase subunit II (MT-CO2/COX2); together with SCO1, facilitates the incorporation of copper into the Cu(A) site of MT-CO2/COX2 (PubMed:15229189, PubMed:17189203, PubMed:19336478, PubMed:35750769). Could also act as a thiol-disulfide oxidoreductase to regulate the redox state of the cysteines in SCO1 during maturation of MT-CO2/COX2 (PubMed:19336478)

Mitochondrion inner membrane

Mitochondrial complex IV deficiency, nuclear type 2

An autosomal recessive, severe mitochondrial disorder characterized by hypotonia, global developmental delay, hypertrophic cardiomyopathy, lactic acidosis, gliosis, and neuronal loss in basal ganglia, brainstem and spinal cord. Serum lactate is increased, and laboratory studies show decreased mitochondrial complex IV protein and activity levels in various tissues, including heart and skeletal muscle. Most patients die in infancy of cardiorespiratory failure.

Copper metallochaperone essential for the maturation of cytochrome c oxidase subunit II (MT-CO2/COX2). Together with SCO2, involved in delivering copper to the Cu(A) site on MT-CO2/COX2 (PubMed:15229189, PubMed:15659396, PubMed:16735468, PubMed:17189203, PubMed:19336478). Plays an important role in the regulation of copper homeostasis by controlling the abundance and cell membrane localization of copper transporter CTR1 (By similarity)

Mitochondrion inner membrane

Mitochondrial complex IV deficiency, nuclear type 4

An autosomal recessive mitochondrial disorder characterized by hypotonia, encephalopathy, metabolic acidosis, poor feeding, hepatomegaly, and hypertrophic cardiomyopathy in some patients. Death occurs in infancy. Patient tissues show decreased levels and activity of mitochondrial respiratory complex IV.

Involved in the maturation of the mitochondrial respiratory chain complex IV subunit MT-CO2/COX2. Thereby, may regulate early steps of complex IV assembly. Mitochondrial respiratory chain complex IV or cytochrome c oxidase is the component of the respiratory chain that catalyzes the transfer of electrons from intermembrane space cytochrome c to molecular oxygen in the matrix and as a consequence contributes to the proton gradient involved in mitochondrial ATP synthesis. May also be required for

Mitochondrion intermembrane space

Mitochondrial complex IV deficiency, nuclear type 13

An autosomal recessive, infantile disorder with a fatal course in the first weeks of life, characterized by hypertrophic cardiomyopathy, left ventricular non-compaction, lactic acidosis, metabolic hypotonia, and mitochondrial complex IV deficiency.

Assembly factor for cytochrome c oxidase (respiratory chain complex IV) (PubMed:21457908, PubMed:35750769). Stabilizes an early formation of cytochrome c oxidase assembly factors, until it is displaced by the metallochaperone copper-delivery protein COX17 (PubMed:35750769)

Mitochondrion intermembrane space

Mitochondrial complex IV deficiency, nuclear type 9

An autosomal recessive, infantile disorder with a fatal course in the first weeks of life, and characterized by hypertrophic cardiomyopathy and mitochondrial complex IV deficiency. Postmortem microscopic investigations show accumulation of lipid droplets in cardiomyocytes and mitochondrial proliferation.

Catalyzes the second reaction in the biosynthesis of heme A, a prosthetic group of mitochondrial cytochrome c oxidase (CcO) (PubMed:12474143). Heme A is synthesized from heme B by two sequential enzymatic reactions catalyzed by heme O synthase (HOS) and heme A synthase (HAS). HAS catalyzes the conversion of heme O to heme A by two successive hydroxylations of the methyl group at C8, in a reaction that involves matrix ferredoxin and ferredoxin reductase. The first hydroxylation forms heme I, the

Mitochondrion inner membrane

Mitochondrial complex IV deficiency, nuclear type 6

An autosomal recessive multisystem disorder with variable manifestations. Some patients present in the neonatal period with encephalomyopathic features, whereas others present later in the first year of life with developmental regression. Clinical features include microcephaly, encephalopathy, hypertrophic cardiomyopathy, persistent lactic acidosis, respiratory distress, hypotonia and seizures. Serum lactate is increased, and laboratory studies show decreased mitochondrial complex IV protein and activity levels.