Complex IV, also known as cytochrome c oxidase (COX), is the fourth critical component of the ETC in oxidative phosphorylation. It is the last and final protein complex in the ETC, responsible for transferring electrons from cytochrome c to molecular oxygen (O2) and reducing O2 to water (H2O). The transfer of electrons through Complex IV is a key step in the generation of a proton motive force, which drives ATP synthesis by ATP synthase. Complex IV receives electrons from cytochrome c, located in the intermembrane space of the mitochondria. Cytochrome c serves as a mobile electron carrier, shuttling electrons between Complex III and Complex IV. The transfer of electrons from cytochrome c to Complex IV is a redox reaction that involves heme groups within the complex. The heme groups in Complex IV act as electron carriers, facilitating the stepwise transfer of electrons to the oxygen-binding site. The primary function of Complex IV is to reduce molecular oxygen (O2) to water (H2O) in a process known as oxygen reduction. This step is crucial for the final disposal of electrons and protons in the ETC, as oxygen serves as the terminal electron acceptor. During oxygen reduction, electrons from cytochrome c are transferred through a series of heme groups in Complex IV. The final electron transfer occurs to the binuclear centre of Complex IV, where molecular oxygen (O2) is reduced to two molecules of water (H2O). This process consumes four electrons and four protons, and each oxygen molecule binds to two electrons and two protons. As electrons are transferred through Complex IV during oxygen reduction, protons are pumped across the inner mitochondrial membrane from the matrix to the intermembrane space. This process contributes to the establishment of the proton motive force, a proton concentration gradient and membrane potential, which is essential for ATP synthesis. The pumping of protons during oxygen reduction is coupled to the transfer of electrons through heme groups in Complex IV. The energy released during electron transfer is then used to actively translocate protons against their concentration gradient, leading to the accumulation of protons in the intermembrane space. Complex IV is a large multisubunit protein complex, and its assembly is a highly regulated process. Mutations in genes encoding subunits of Complex IV or factors involved in its assembly can lead to impaired electron transfer and reduced ATP production. Additionally, Complex IV is sensitive to various factors, including changes in oxygen levels and redox state, and is regulated to optimize energy production and minimize the production of reactive oxygen species (ROS). Dysfunction of Complex IV has been linked to various human diseases, including mitochondrial disorders and neurodegenerative conditions. Defects in Complex IV can lead to impaired oxygen reduction, causing an imbalance in the electron transport chain and the accumulation of electrons, leading to increased production of ROS. This oxidative stress can result in cellular damage and contribute to disease pathogenesis. We offer a wide product range of research reagents for studying Complex IV, including COX5A antibodies, Surf1 antibodies, and MTCO2 antibodies. Explore our full Complex IV product range below and discover more, for less.