SELECTIVE MODULATION OF MEMBRANE SPHINGOMYELIN FATTY-ACID TURNOVER BYNIGERICIN - A STUDY IN THE RAT RETICULOCYTE

Exposure of rat reticulocytes to Nigericin produced a selective modula tion of fatty acid incorporation into sphingomyelin (SM) of the cell m embrane, via changes in SM acylation kinetics. At physiological fatty acid concentration, Nigericin accelerated 8-fold SM acylation by decre asing the apparent Km for oleate from 14.7 mu M to 2.0 mu M. The respo nse was diminished in high K+-containing media, suggesting an effect o f Nigericin as Kf transporter. This constitutes a novel piece of evide nce for the important role of ions in SM metabolism.