Abstract

 Sterols are essential lipid components for the cell membrane. In addition to their structural roles, they are critical signaling molecules that regulate metabolism, development, and homeostasis. Due to the functions of sterols being concentrationdependent, the biosynthesis of sterols is tightly controlled. Here, we reviewed the biosynthesis processes of sterols (squalene, lanosterol, ergosterol, carotenoid, and polyprenols) and analyzed the key and limited enzymes in these processes. Although various sterols are identified in nature, their basic synthesis pathways appear to be conserved. Squalene is the key intermediate in the biosynthesis of sterols, and the cyclization of squalene into lanosterol (animals and fungi) or cycloartenol (plants), producing various types of terpenoids. In addition to the synthesis processes of sterols, how to enhance sterols production was also discussed, which provides the strategy for the industrial production of sterol products.