Cytochrome c oxidase subunit 2

Subunit of cytochrome c oxidase

Cytochrome c oxidase subunit 2 (COX2) is a component of the cytochrome c oxidase complex, which is the last enzyme in the electron transport chain of mitochondria. This enzyme plays a crucial role in the process of oxidative phosphorylation, where it facilitates the transfer of electrons from cytochrome c to oxygen, contributing to the generation of ATP.

Structure

Map of the human mitochondrial genome

Cytochrome c oxidase subunit 2 is encoded by the mitochondrial DNA and is one of the three subunits that form the core of the cytochrome c oxidase complex. The human mitochondrial genome, as depicted in the adjacent image, includes the gene for COX2, which is located between the genes for cytochrome c oxidase subunit 1 and cytochrome c oxidase subunit 3.

The COX2 protein is an integral membrane protein that spans the inner mitochondrial membrane. It contains two copper centers, known as Cu_A, which are essential for its function in electron transfer. The structure of COX2 allows it to interact with cytochrome c and facilitate the transfer of electrons to the catalytic subunit, COX1.

Function

Structure of cytochrome c oxidase

The primary function of cytochrome c oxidase subunit 2 is to serve as an electron transfer agent within the cytochrome c oxidase complex. Electrons are transferred from cytochrome c, which is located in the intermembrane space, to the Cu_A center of COX2. From there, the electrons are passed to the heme a and heme a3-Cu_B centers in COX1, where the reduction of oxygen to water occurs.

This electron transfer is coupled with the pumping of protons across the inner mitochondrial membrane, contributing to the proton gradient that drives ATP synthesis by ATP synthase. The efficiency and regulation of this process are critical for cellular energy production and are influenced by various factors, including the availability of oxygen and the integrity of the mitochondrial membrane.

Clinical significance

Mutations in the gene encoding cytochrome c oxidase subunit 2 can lead to mitochondrial disorders, which are often characterized by defects in energy metabolism. These disorders can manifest in a variety of ways, including muscle weakness, neurodegenerative diseases, and metabolic syndromes. Understanding the structure and function of COX2 is therefore important for diagnosing and developing treatments for these conditions.

Related pages

• Cytochrome c oxidase
• Electron transport chain
• Mitochondrial DNA
• Oxidative phosphorylation