Transport of phospholipids between subcellular membranes of wild-type yeast cells and of the phosphatidylinositol transfer protein-deficient strain Saccharomyces cerevisiae sec 14.

The transfer of glycerophospholipids between microsomes and mitochondria, and from internal membranes to the plasma membrane of Saccharomyces cerevisiae was characterized. Cellular energy production was found to be essential for intracellular translocation of phospholipids, but neither a membrane potential nor an intact cytoskeleton are required for this process. Using the temperature-sensitive mutant strain Saccharomyces cerevisiae sec 14, which is defective in the phosphatidylinositol transfer protein, it could be demonstrated that this protein is not involved in the transport of phosphatidylinositol and phosphatidylcholine from internal membranes to the plasma membrane. Our results also confirm earlier findings that phosphatidylinositol and phosphatidylcholine can be delivered to the plasma membrane in a process independent of the flux of vesicles competent for protein secretion.