Squalene synthase (SQS) is a key enzyme in the sterol biosynthesis pathway, belonging to the lipid metabolism enzyme family. It catalyzes the synthesis of squalene, a precursor in the biosynthesis of sterols and other terpenoid compounds. SQS is primarily located in the endoplasmic reticulum, participating in various biological reactions and signaling pathways by regulating the production of cholesterol and other sterol compounds. The expression of this enzyme is tissue-specific, and its activity and expression levels are tightly regulated. Mutations in the gene may affect enzyme activity, leading to cholesterol metabolism disorders and related diseases.