Net transfer of phospholipid by the nonspecific phospholipid transfer proteins from bovine liver

The nonspecific phospholipid transfer proteins from bovine liver catalyze net transfer of phosphatidylcholine and phosphatidylinositol from phosphatidylcholine/phosphatidylinositol multilamellar vesicles (9 : 1; mol/mol) to either intact or totally delipidated human high density lipoprotein. Under indentical conditions, the phosphatidylcholine-specific exchange protein from bovine liver and the phosphatidylinositol/phosphatidylcholine exchange protein from beef heart do not enhance the net transfer of labeled phosphatidylcholine or phosphatidylinositol from multilamellar vesicles to delipidated high density lipoprotein, but do catalyze phospholipid exchange between multilamellar vesicles and intact high density lipoprotein consistent with their reported specificities. In the presence of nonspecific transfer proteins net transfer of mass in also observed from phosphatidylcholine unilamellar vesicles to rat liver inner mitochondrial membranes plus matrix. These are the first exchange proteins demonstrated to have net mass transfer capability.