COX5B


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. 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. The protein is a subunit of Complex IV, which consists of 13 mitochondrial- and nuclear-encoded subunits. The sequence of subunit Vb is well conserved and includes three conserved cysteines that coordinate the zinc ion. Two of these cysteines are clustered in the C-terminal section of the subunit.

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.

Function

Cytochrome c oxidase 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.
Summary reaction:

Clinical significance

and COX5B are involved in the regulation of cancer cell metabolism by Bcl-2.
The Trans-activator of transcription protein of human immunodeficiency virus inhibits cytochrome c oxidase activity in permeabilized mitochondria isolated from both mouse and human liver, heart, and brain samples.

Interactions

COX5B has been shown to interact with Androgen receptor.