Fluorescently labelled ether phospholipid (1-O-alkyl/alkenyl-2-acyl- glycerophosphocholine) readily internalizes at low temperatures (2 degrees C) after insertion into the plasma membrane of cultured fibroblasts. This fate differs markedly from that of its diacyl phospholipid analogue, which remains associated with the plasma membrane under similar conditions. Analysis by thin-layer chromatography reveals that the translocation involves transfer of the intact ether phosphatidylcholine molecules. Relative to control cells, a 2-fold increase of ether phosphatidylcholine uptake was noted when plasmalogen deficient fibroblasts were used. Back-exchange experiments demonstrate that more than 60% of the cell-associated ether lipid is translocated within the cells, irrespective of the cell strain that was used. The potential mechanism by which the translocation process is accomplished is discussed.
Cell Membrane Cells, Cultured