Cholesterol Perturbs Lipid Bilayers Non-Universally

Despite the popular perception that cholesterol is unhealthy, it is a vital component in the membranes of mammalian cells, with concentrations varying up to 50 mol % of the total lipid in healthy cell plasma membranes [1]. Cholesterol is considered to be a key molecule for the formation of small rafts that have been implicated in providing favorable nano environments to facilitate biochemical functioning of membrane proteins [2]. Cholesterol is important in producing macroscopic fluidfluid phase separation that has been so strikingly visualized by fluorescence microscopy [3]. Not surprisingly, there is a large biophysical literature of cholesterol in lipid bilayers [4,5].