Cholesterol (membrane cholesterol)

Cholesterol is a **major sterol lipid** component of animal cell membranes, accounting for up to 40% of the lipid content in some cell types[1][7]. It is an **amphipathic molecule** with a hydrophilic hydroxyl group that aligns with the phospholipid head groups and a bulky hydrophobic ring structure embedded among the fatty acid tails of the bilayer[5]. Cholesterol plays essential roles in regulating **membrane fluidity, elasticity, permeability, and structural integrity**[1][7][9]. Its effects are temperature-dependent: at high temperatures, cholesterol restricts phospholipid movement and **reduces fluidity and permeability**; at low temperatures, it **prevents membrane solidification** by hindering close packing of the phospholipid tails[7][9]. Cholesterol also facilitates the formation of specialized membrane microdomains known as **lipid rafts**, which organize membrane proteins and are important for processes such as **signal transduction, endocytosis, and viral entry**[7][9]. Cholesterol influences **membrane fusion and fission**, important for intracellular trafficking and vesicle release, and can alter the membrane's mechanical properties (bending rigidity, curvature) in a manner dependent on the lipid composition[1][2][3][4]. Unlike typical therapeutic targets (such as receptors or enzymes), **membrane cholesterol itself is not a drug target, but is critical for fundamental cell biology and implicated in several diseases as part of complex lipid and membrane processes**[1][3][8]. Overall, "membrane cholesterol" refers to a **structural lipid molecule** essential for the proper function and physical properties of cell membranes, but it is not a protein, receptor, or classically druggable target.

Other names

Cholesterolmembrane-associated cholesterolplasma membrane cholesterolcholesterol lipid