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COX5A
Identifiers
Aliases	COX5A, COX, COX-VA, VA, cytochrome c oxidase subunit 5A, MC4DN20
External IDs	OMIM: 603773; MGI: 88474; HomoloGene: 37905; GeneCards: COX5A; OMA:COX5A - orthologs
Gene location (Human)
Chr.	Chromosome 15 (human)
End	74,938,083 bp
Gene location (Mouse)
Chr.	Chromosome 9 (mouse)
End	57,439,709 bp
RNA expression pattern
	Top expressed in
	right ventricle; ; left ventricle; ; biceps brachii; ; mucosa of sigmoid colon; ; mucosa of transverse colon; ; right auricle; ; apex of heart; ; thoracic diaphragm; ; Skeletal muscle tissue of biceps brachii; ; jejunal mucosa;
	Top expressed in
	atrioventricular valve; ; endocardial cushion; ; medial vestibular nucleus; ; deep cerebellar nuclei; ; tunica adventitia of aorta; ; lateral geniculate nucleus; ; intercostal muscle; ; myocardium of ventricle; ; pontine nuclei; ; lateral hypothalamus;
	More reference expression data
	n/a
Gene ontology
Molecular function	electron transfer activity; protein binding; metal ion binding; cytochrome-c oxidase activity;
Cellular component	myelin sheath; mitochondrion; membrane; mitochondrial inner membrane; mitochondrial respiratory chain complex IV;
Biological process	proton transmembrane transport; mitochondrial electron transport, cytochrome c to oxygen;
	Sources:Amigo / QuickGO
Orthologs
	9377
	12858
	ENSG00000178741
	ENSMUSG00000000088
	P20674
	P12787
	NM_004255
	NM_007747
	NP_004246
	NP_031773
	Wikidata
View/Edit Human	View/Edit Mouse

Cytochrome c oxidase subunit 5a is a protein that in humans is encoded by the COX5A gene. Cytochrome c oxidase 5A is a subunit of the cytochrome c oxidase complex, also known as Complex IV, the last enzyme in the mitochondrial electron transport chain.^[5]

Structure

The COX5A gene, located on the q arm of chromosome 15 in position 24.1, is made up of 5 exons and is 17,880 base pairs in length.^[5] The COX5A protein weighs 17 kDa and is composed of 150 amino acids.^[6]^[7] The protein is a subunit of Complex IV, which consists of 13 mitochondrial- and nuclear-encoded subunits.^[5]

Function

Cytochrome c oxidase (COX) is the terminal enzyme of the mitochondrial respiratory chain. It is a multi-subunit enzyme complex that couples the transfer of electrons from cytochrome c to molecular oxygen and contributes to a proton electrochemical gradient across the inner mitochondrial membrane to drive ATP synthesis via protonmotive force. The mitochondrially-encoded subunits perform the electron transfer of proton pumping activities. The functions of the nuclear-encoded subunits are unknown but they may play a role in the regulation and assembly of the complex.^[5]

Summary reaction:

4 Fe²⁺-cytochrome c + 8 H⁺_in + O₂ → 4 Fe³⁺-cytochrome c + 2 H₂O + 4 H⁺_out^[8]

Clinical significance

COX5A (this gene) and COX5B are involved in the regulation of cancer cell metabolism by Bcl-2. COX5A interacts specifically with Bcl-2, but not with other members of the Bcl-2 family, such as Bcl-xL, Bax or Bak.^[9]

The Trans-activator of transcription protein (Tat) of human immunodeficiency virus (HIV) inhibits cytochrome c oxidase (COX) activity in permeabilized mitochondria isolated from both mouse and human liver, heart, and brain samples.^[10]