COX5B

Cytochrome c oxidase subunit 5B, mitochondrial is an is_associated_with::enzyme that in humans is encoded by the COX5B is_associated_with::gene. Cytochrome c oxidase 5B is a subunit of the cytochrome c oxidase complex, also known as is_associated_with::Complex IV, the last enzyme in the mitochondrial is_associated_with::electron transport chain.

Structure
The COX5B gene, located on the q arm of is_associated_with::chromosome 2 in position 11.2, is made up of 4 is_associated_with::exons and is 2,137 is_associated_with::base pairs in length. The COX5B is_associated_with::protein weighs 14 kDa and is composed of 129 is_associated_with::amino acids. The protein is a subunit of is_associated_with::Complex IV, which consists of 13 mitochondrial- and nuclear-encoded subunits.

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.

Summary reaction:
 * 4 Fe2+-cytochrome c + 8 H+in + O2 → 4 Fe3+-cytochrome c + 2 H2O + 4 H+out

Clinical significance
is_associated_with::COX5A and COX5B are involved in the regulation of cancer cell metabolism by is_associated_with::Bcl-2.

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.

Interactions
COX5B has been shown to interact with is_associated_with::Androgen receptor.