Difference in plasma membrane structure between two sublines of ehrlich-lettrè ascites tumor cells

The plasma membranes of the glycogen-free and the glycogen-containing subline of Ehrlich-Lettrè ascites cells were purified and compared with respect to their enzyme activity, chemical, lipid and protein composition, and membrane fluidity. Both membrane fractions differed in a number of parameters which are discussed as differences in the expression of malignant transformation of the two sublines. 1. The 5′-nucleotidase activity was 3–5-times higher and the sialic acid content 3-times lower in the glycogen-containing than in the glycogen-free subline. 2. Differences were also observed with respect to the phospholipid composition, that is in the relative proportions of mainly phosphatidylcholine, -inositol and -serine. 3. The fatty acid spectrum of the two sublines differed in the C-18 series and in the percentage of polyunsaturated acids, which was about 6% lower in the glycogen-containing line. 4. Measurements of fluorescence polarization (P) using 1,6-diphenyl-1,3,5-hextriene as probe generally gave higher P values, indicating a decreased membrane fluidity for the plasma membranes of the glycogen-containing subline both below and above the transition temperature at 33°C. 5. Polyacrylamide gel electrophoresis revealed different protein patterns mainly in the molecular weight range of around 90 000 and in the range between 31 000 and 14 000.