Phospholipid-transfer activity in type II cells isolated from adult rat lung

The soluble fraction from adult rat lung type II cells stimulated the transfer of various phospholipids between either liposomes or rat lung microsomes and rat lung mitochondria. Compared to whole lung, type II cells are highly enriched in transfer activity suggesting that phospholipid-transfer proteins play a role in the transport of surfactant phospholipids. Sephadex chromatography of pH 5.1 supernatant from type II cells yielded only one fraction catalysing the transfer of phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine, while chromatography of pH 5.1 supernatant from whole lung yielded in addition a specific phosphatidylcholine-transfer and a specific phosphatidylglycerol-transfer protein.