COX5B
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Cytochrome c oxidase subunit 5B, mitochondrial is an enzyme in humans that is a subunit of the cytochrome c oxidase complex, also known as Complex IV, the last enzyme in the mitochondrial electron transport chain.[1] In humans, cytochrome c oxidase subunit 5B is encoded by the COX5B gene.
Structure
The enzyme weighs 14 kDa and is composed of 129 amino acids.[2][3] The protein is a subunit of Complex IV, which consists of 13 mitochondrial- and nuclear-encoded subunits.[1] The sequence of subunit Vb is well conserved and includes three conserved cysteines that coordinate the zinc ion.[4][5] Two of these cysteines are clustered in the C-terminal section of the subunit.
Gene
Template:Infobox gene The COX5B gene, located on the q arm of chromosome 2 in position 11.2, is made up of 4 exons and is 2,137 base pairs in length.[1]
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 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.[1]
Summary reaction:
- 4 Fe2+-cytochrome c + 8 H+in + O2 → 4 Fe3+-cytochrome c + 2 H2O + 4 H+out[6]
Clinical significance
COX5A and COX5B are involved in the regulation of cancer cell metabolism by Bcl-2.[7]
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.[8]
Interactions
COX5B has been shown to interact with Androgen receptor.[9]
References
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Further reading
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External links
- Template:UCSC gene info
- Mass spectrometry characterization of COX5B at COPaKB
- Cytochrome c oxidase subunit Vb in PROSITE
- Template:PDBe-KB2
This article incorporates text from the United States National Library of Medicine, which is in the public domain.