Key enzyme in the cholesterol biosynthesis pathway. Catalyzes the cyclization of (S)-2,3 oxidosqualene to lanosterol, a reaction that forms the sterol nucleus (PubMed:14678783). Through the production of lanosterol may regulate lens protein aggregation and increase transparency (By similarity). (S)-2,3-epoxysqualene = lanosterol Inhibited by the benzophenone containing OSC inhibitor Ro48-8071 and to a lesser extent by other benzophene containing inhibitors. Optimum pH is 7.4. Active from pH 5.0 to 10.0. Optimum temperature is 37 degrees Celsius. Active from 25 to 50 degrees Celsius. Terpene metabolism; lanosterol biosynthesis; lanosterol from farnesyl diphosphate: step 3/3. Monomer. Detected in the liver (at protein level). The N-terminus is blocked. Belongs to the terpene cyclase/mutase family.