Phospholipid transfer proteins in rat lung. Identification of a protein specific for phosphatidylglycerol

From the soluble fraction of a rat lung homogenate, two proteins were partially purified which catalyzed the transfer of phosphatidylglycerol between liposomes and rat lung mitochondria. One protein was specific for phosphatidylglycerol, the other also catalyzed the transfer of phosphatidylcholine and phosphatidylethanolamine. The soluble fraction from rat liver also contained the nonspecific, but not the specific phosphatidylglycerol-transfer protein. It is suggested that the specific phosphatidylglycerol-transfer protein, as well as the phosphatidylcholine-transfer protein, which is also present in rat lung, contribute in the lung to the biogenesis of lamellar bodies, the organelles where surfactant phosphatidylcholine and phosphatidylglycerol are stored prior to secretion onto the alveolar surface.