Figure 4.

Representative in vitro ³¹P-NMR spectra (expanded scale from −1 to 4 ppm) of a lipid extract from sycamore cells. The spectra, recorded at 20°C, are the results of 256 transients (9 min). Lipid extracts were prepared from a standard, exponentially growing suspension culture (9 g wet weight) according to the procedure described in “Materials and Methods.” A, Control cells at pH 6.0; B, cells incubated for 7 d with 5 mm [¹³C]methanol at pH 6.0. Note that the phospholipid composition of cells was not modified by the presence of [¹³C]methanol in the growth medium. Peak assignments are as follows: PG, phosphatidylglycerol; DPG, diphosphatidylglycerol (cardiolipin); PE, phosphatidylethanolamine; PS, phosphatidyl-Ser; PI, phosphatidylinositol; PC, phosphatidylcholine. The signal at 2.18 ppm next to PS was not ascribed to a known phospholipid.