Cholesterol-13C3 is a 13C-labeled version of cholesterol. Cholesterol is a primary sterol in mammals and constitutes 20-25% of the plasma membrane structure. The plasma membrane exhibits high permeability to water but is relatively impermeable to ions and protons. Cholesterol plays a crucial role in determining membrane fluidity and permeability characteristics, as well as affecting the function of transport and signaling proteins. Additionally, cholesterol acts as an endogenous agonist of estrogen-related receptor alpha (ERRα).