Role of lipid ordered/disordered phase coexistence in pulmonary surfactant function

Biochim Biophys Acta. 2012 Nov;1818(11):2550-62. doi: 10.1016/j.bbamem.2012.05.024. Epub 2012 May 31.


The respiratory epithelium has evolved to produce a complicated network of extracellular membranes that are essential for breathing and, ultimately, survival. Surfactant membranes form a stable monolayer at the air-liquid interface with bilayer structures attached to it. By reducing the surface tension at the air-liquid interface, surfactant stabilizes the lung against collapse and facilitates inflation. The special composition of surfactant membranes results in the coexistence of two distinct micrometer-sized ordered/disordered phases maintained up to physiological temperatures. Phase coexistence might facilitate monolayer folding to form three-dimensional structures during exhalation and hence allow the film to attain minimal surface tension. These folded structures may act as a membrane reserve and attenuate the increase in membrane tension during inspiration. The present review summarizes what is known of ordered/disordered lipid phase coexistence in lung surfactant, paying attention to the possible role played by domain boundaries in the monolayer-to-multilayer transition, and the correlations of biophysical inactivation of pulmonary surfactant with alterations in phase coexistence.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Lipids / chemistry*
  • Proteins / chemistry
  • Pulmonary Alveoli / physiology
  • Pulmonary Surfactants / metabolism*
  • Surface Tension


  • Lipids
  • Proteins
  • Pulmonary Surfactants