The effect of N-terminal fragments of immunophilin on phospholipid composition of rat brain

Rat brain slices have been incubated in the presence of water-soluble synthetic peptide fragments corresponding to residues 1-9 and 1-15 of the N-terminus of immunophilin and the effects on the phospholipid composition examined. During a 2 h incubation in the presence of 1 nM, 0-1 mu M and 10 mu M concentrations of the peptides there were significant and dose-dependent decreases in the amounts of phosphatidylcholine and phosphatidylethanolamine and increases in the amounts of phosphatidylserine and, to a lesser extent, phosphatidylinositol, cardiolipin and lysophosphatidylcholine. The overall decrease in the neutral phospholipids and increase in the acidic phospholipids tended to counteract any change in the phospholipid composition of the tissue. The results are discussed in terms of the possible effects of immunophilin on modulating phospholipid turnover in brain cell membranes.