SPONTANEOUS FORMATION OF INTERFACIAL LIPID-PROTEIN MONOLAYERS DURING ADSORPTION FROM VESICLES

Spread and adsorbed monolayers of lipid-protein mixtures have served a s models for biomembranes and pulmonary surfactant, but their similari ty was unclear, Epifluorescence microscopy of monolayers spontaneously adsorbed from vesicles of dipalmitoylphosphatidylcholine or dipalmito ylphosphatidylcholine plus surfactant protein C (SP-C) showed gas, liq uid expanded, and liquid condensed (LC) domains, The shapes and distri bution of LC domains in the adsorbed and solvent-spread monolayers wer e quite similar. Labeled SP-C adsorbed into the air-water interface in the company of the lipids, In both forms of monolayers, SP-C occupied the fluid phase and reduced the size and amount of the LC domains. Th e properties suggest that these adsorbed and spread monolayers are ana logous to one another.