Squalene epoxidase catalyzes the first oxygenation step in sterol biosynthesis and is thought to be one of the rate-limiting enzymes in this pathway.

This enzyme contains a loosely bound FAD flavin and obtains electrons from NADPH-cytochrome P450 reductase, rather than binding NADPH directly.

The alternative squalene epoxidase belongs to the fatty acid hydroxylase superfamily and obtains electrons from cytochrome b5.

[10] In baker's yeast (Saccharomyces cerevisiae), squalene epoxidase is localized to both the endoplasmic reticulum and lipid droplets.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.