Effect of hydration on the structure of caveolae membranes

In situ energy dispersive x-ray diffraction was used to investigate the effect of hydration on the structure of caveolae membranes. The structure of caveolae membrane was found to be strongly dependent on hydration. At low hydration two lamellar phases with distinct repeat spacings were found to coexist with segregated cholesterol crystallites. Upon hydration, the lamellar phases did swell, while diffraction peak of cholesterol crystals disappeared suggesting that cholesterol molecules redistributed homogeneously within the caveolae membrane. At full hydration, unbinding of caveolae membrane occurred. Upon dehydration the system returned to the bound state, demonstrating that the unbinding transition is fully reversible.