What is the role of cholesterol in the plasma membrane?

Cholesterol plays a crucial role in maintaining the fluidity of the plasma membrane. It is intercalated among the phospholipids in the bilayer, where its rigidity helps to stabilize the membrane structure. By doing so, cholesterol prevents the tails of the phospholipids from packing too closely together, which would otherwise make the membrane too rigid. At the same time, cholesterol also helps to maintain membrane fluidity at varying temperatures, preventing it from becoming too fluid at high temperatures and too solid at low temperatures. This balance is essential for optimal membrane function, including the proper functioning of membrane proteins and the overall integrity of the cell.

While cholesterol has several other roles in the body, such as serving as a precursor for hormone synthesis and playing a part in signal transduction pathways, its primary and critical function in the plasma membrane is to maintain its fluidity.