Plasma membranes: does one model fit all?

concentrations. Recently, a new model for plasma membranes (PMs) was introduced. It is based on studies with human erythrocytes and suggests that there is a 50% overabundance of lipids with two hydrophobic chains in the cytosolic leaflet, compensated by the presence of three times more cholesterol in the outer leaflet. In this opinion article, we discuss the large differences in lipid composition between erythrocytes and other cell types, the assumptions used to reach the new membrane model, and whether this model would fit PMs of other cell types.