The interaction between cholesterol and surfactant protein-c in lung surfactant

surfactant membranes, including the segregation of fluid-ordered and fluid-disordered phases.

However, an excess of cholesterol has been associated with impaired surface activity both in

surfactant models and in surfactant from injured lungs. It has also been reported that surfactant

protein SP-C interacts with cholesterol in lipid/protein interfacial films. In the present study, we

have analyzed the effect of SP-C on the thermodynamic properties of phospholipid membranes

containing cholesterol and on the ability of lipid/protein complexes containing surfactant

proteins and cholesterol to form and re-spread interfacial films capable of producing very low

surface tensions upon repetitive compression-expansion cycling. We have also analyzed the effect of cholesterol on the

structure, orientation and dynamic properties of SP-C embedded in physiologically relevant

model membranes.