Figure 3

Phospholipid metabolism in phagosomal preparations. A. A phagosomal preparation was incubated with γ32P.ATP and 0.1 mM unlabelled ATP at 20°C for different periods of time (min). Phospholipids were extracted with chloroform:methanol and resolved by TLC. The plate was exposed for 8 h (left) or 24 h (right). B. A phagosomal preparation was incubated with ¹⁴C(glycerol).PA (14C.PA) or ³H(choline).PC (3H.PC), 0.2 mM unlabelled ATP and (when indicated) 1 mM CTP and 1 mM inositol for different periods of time (min). Phospholipids were extracted and resolved by TLC. C. A phagosomal preparation was incubated with γ32P.ATP and 0.2 mM unlabelled ATP in the presence of different concentrations of unlabelled PC, PA, and DAG (μM) for 15 min. Phospholipids were extracted and resolved by TLC. Radiolabelled PA and PC were included in the right most lane as markers. Only the upper part of the TLC plate is shown. D. In experiments similar to the one shown in C, different concentrations of unlabelled lipids (μM) were included in the assay. The amount of ³²P incorporated in PIP and PIP2 was quantified and expressed as a percentage of the incorporation observed when no lipid was added. The values represent the mean of 2 or 3 independent experiments (error bars: range for N = 2, SEM for N = 3).