Uptake of l‐Glutamate and Taurine in Neuroblastoma Cells with Altered Fatty Acid Composition of Membrane Phospholipids

Effects of altered composition of membrane lipids on high‐affinity uptake of l ‐glutamate and taurine were studied in an established neuroblastoma cell line M 1 . Increase in participation of certain fatty acids (20: 5ω3 and 22: 5ω3) as constituents of membrane lipids resulted in a fourfold increase in the maximum initial rate of l ‐glutamate uptake (V max ) while increase in V max of taurine uptake was much smaller. Neither structural requirements of l ‐glutamate uptake nor passive permeability of the membrane to l ‐glutamate or taurine seemed to be influenced by the alterations in the lipid composition. Since increased proportions of 20: 5ω3 and 22: 5ω3 in the membrane phosphatides caused no dramatic changes in kinetic parameters of taurine uptake and incorporation of either linoleic or linolenic acid alone into the phosphatides had only a relatively small effect on some of the measured parameters, the possibility of a specific relationship between 22: 5ω3 and/or 20: 5ω3 and l ‐glutamate uptake is discussed. Unlike l ‐glutamate uptake systems in other preparations, the high‐affinity uptake system of l ‐glutamate in neuroblastoma cells did not readily accept l ‐aspartate as a substrate.