Related Experiment Video
Updated: Jan 11, 2026
06:35
Author Spotlight: Innovative Techniques for ROS Detection and Implications for Platelet Research
Published on: March 29, 2024
1.1K
The superoxide-generating NADPH oxidase: structural aspects and activation mechanism
1DRDC/BBSI (UMR 5092), CEA-Grenoble, France. umr5092@dsvsud.cea.fr
Cellular and Molecular Life Sciences : CMLS
|November 21, 2002
Summary
Flavocytochrome b558, the core of the NADPH oxidase, generates superoxide in phagocytes. Defects cause chronic granulomatous disease, highlighting its role in host defense.
Area of Science:
- Biochemistry
- Immunology
- Cell Biology
Background:
- Flavocytochrome b558 is the catalytic component of the phagocyte respiratory-burst oxidase.
- This enzyme complex reduces O2 to superoxide anion (O2-) in a NADPH-dependent manner.
- It is a membrane-anchored heterodimer composed of gp91phox and p22phox subunits.
Purpose of the Study:
- To review the structural organization, kinetics, activation mechanisms, and biosynthesis regulation of O2(-)-generating flavocytochrome b558.
- To discuss the role of homologous Nox and Duox proteins in non-phagocytic cells.
Main Methods:
- Literature review of current knowledge on flavocytochrome b558.
- Analysis of the structural components and their functions.
- Discussion of genetic defects and their clinical manifestations.
Main Results:
- Flavocytochrome b558 comprises gp91phox (containing FAD, hemes b, and NADPH binding site) and p22phox (docking site for cytosolic proteins).
- Assembly with cytosolic proteins (p67phox, p47phox, p40phox, Rac) upon cell stimulation activates O2- generation.
- Defects in genes for gp91phox, p22phox, p67phox, or p47phox lead to chronic granulomatous disease.
Conclusions:
- Flavocytochrome b558 is crucial for host defense against pathogens via O2- and derived metabolites.
- Homologues (Nox, Duox) in non-phagocytic cells have roles in signal transduction and proton transport.
- Further investigation into Nox/Duox functions in signal transduction is warranted.
More Related Videos
Related Concept Videos
01:26Oxygenic Photosynthesis
690
Oxygenic photosynthesis is a fundamental process in which light energy is harnessed to drive the oxidation of water, leading to the production of molecular oxygen (O₂), adenosine triphosphate (ATP), and nicotinamide adenine dinucleotide phosphate (NADPH). This process is essential for sustaining aerobic life on Earth and is primarily carried out by cyanobacteria, algae, and plants. The core of oxygenic photosynthesis lies in the thylakoid membranes, where chlorophyll pigments facilitate...
690
01:43Electron Transport Chain: Complex III and IV
9.0K
During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...
9.0K
01:41The Supercomplexes in the Crista Membrane
2.9K
The mitochondrial cristae membrane is the primary site for the oxidative phosphorylation (OXPHOS) process of energy conversion mediated through respiratory complexes I to V. These complexes have been widely studied for decades, and it has been proven that they form supramolecular structures called respiratory supercomplexes (SC). These higher-order complexes may be crucial in maintaining the biochemical structure and improving the physiological activity of the individual complexes while...
2.9K
01:29Role of Reduced Coenzymes NADH and FADH₂
16.1K
The energy released from the breakdown of the chemical bonds within nutrients can be stored either through the reduction of electron carriers or in the bonds of adenosine triphosphate (ATP). In living systems, a small class of compounds functions as mobile electron carriers, molecules that bind to and shuttle high-energy electrons between compounds in pathways. The principal electron carriers that will be considered originate from the B vitamin group and are derivatives of nucleotides; they are...
16.1K
01:34The Z-Scheme of Electron Transport in Photosynthesis
13.0K
The light reactions of photosynthesis assume a linear flow of electrons from water to NADP+. During this process, light energy drives the splitting of water molecules to produce oxygen. However, oxidation of water molecules is a thermodynamically unfavorable reaction and requires a strong oxidizing agent. This is accomplished by the first product of light reactions: oxidized P680 (or P680+), the most powerful oxidizing agent known in biology. The oxidized P680 that acquires an electron from the...
13.0K
01:27Photosystem I
69.4K
Although structurally similar to photosystem II (PSII), photosystem I (PSI) is has a different electron supplier and electron acceptor.
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...
69.4K