Biosynthesis of cholesterol and other sterols

Cholesterol and its relatives possessing the 1,2- cyclopentanoperhydrophenanthrene ring system form the sterolome, which comprises a chemical library of more than 1000 natural products found in all forms of eukaryotes and some prokaryotes that serve a myriad of biological functions. Central to the advances of the past two decades is the development of molecular genetic approaches that have witnessed the cloning, primary amino acid sequences, and functional characterization of a large number of enzymes that act on sterol and revealed unexpected inborn errors of cholesterol metabolism. The relevant committed step that distinguishes sterol from isoprenoid-triterpenoid biosynthesis occurs at the cyclization of oxidosqualene. There is still much to learn about sterol biosynthesis and the enzymes involved in the pathway.