Rapid transport of phospholipids across the plasma membrane of Leishmania infantum.

The internalization of fluorescent phospholipid analogs of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), and sphingomyelin (SM) in Leishmania infantum promastigotes was studied. We observed a rapid inward redistribution of NBD-PC, -PE, and -PS across the plasma membrane at 28 and 4 degrees C. This internalization was shown to be independent of the endocytic activity of parasites. Rapid inward movement was coupled to an energy-dependent transporter because it was almost inhibited by depletion of cellular ATP and was blocked after pretreatment with N-ethylmaleimide (NEM). In contrast, NBD-SM traverses the plasma membrane by passive flip-flop. By comparing this pattern of phospholipid transbilayer movement with those known from other eukaryotic cells, candidate lipid transporters are discussed.