[1] It contains FAD and catalyzes the reaction: In its b5-reducing capacity, this enzyme is involved in desaturation and elongation of fatty acids, cholesterol biosynthesis, and drug metabolism.

With the ability to express approximately 1080 base pairs, cytochrome b proteins are commonly studied to analyze mitochondrial DNA and determine phylogenetic relationships across evolution.

[9] Specialized isoforms of the enzyme c5br are heavily functional in the blood to help deliver oxygen to the body's tissue by conformationally changing methemoglobin to hemoglobin.

[10] In living organisms, because methemoglobin (MetHb) is unable to bind oxygen, it must be reduced to hemoglobin (Hb) through the action of the soluble isoform of cytochrome b5 reductase.

It is typically found embedded in the membranes of various cellular compartments, with a domain inserted into the lipid bilayer on the outer leaflet of the endoplasmic reticulum.

[23] While the addition of methylene blue to treat cases of methemoglobinemia has been scientifically tested and proven, there are some side effects to note and monitor with high dosages of the antidote.

[23] Additional studies have found that the use of methylene blue during pregnancy is associated with a high risk of small intestinal atresia, which can be fatal to the fetus.

If symptoms of methemoglobinemia are still present after the second dosage, alternative treatments, including ascorbic acid, exchange transfusion, and hyperbaric oxygen therapy, can be considered.

[23][25] Cytochrome b5 reductase is a prevalent topic in research and clinical tests to understand the additional functions of the enzyme in other metabolic pathways in the body.

A recent study from 2023 used mice as a model to test the extended effects of c5br on oxygen supply in the presence of additional oxidative stress, such as from sickle cell disease or ischemic stroke.

The results showed that c5br not only increases oxygen supply and transport in a wild-type organism but also regulates the erythropoietin response to ischemic stroke.

These findings have made cytochrome b5 reductase a target for future research on managing stroke risk and providing selective advantage for those with genetic disorders such as sickle cell disease.

These results indicate that cytochrome b5 reductase is a new target for new research and development of lipid metabolism and health in living organisms.