CHANGES PRODUCED BY COBRA VENOM CYTOTOXIN ON MORPHOLOGY OF YOSHIDA SARCOMA CELLS

Cobra cytotoxin which preferentially attacks Yoshida sarcoma cells, initially produces swelling of the cells. This is followed by shrinkage of the membrane which is accompanied by release of cytoplasmic RNA and protein. No DNA leaks out. Experiments with chicken erythrocytes and a fluorescent complex of the cytotoxin with Dansyl indicated combination of the cytotoxin with plasma membrane constituents initially. Combination with nuclear constituents occurred later. Phosphatidyl ethanolamine and phosphatidyl serine inhibited cytotoxicity in YS cells, but lecithin had no effect. This evidence suggests that the cytotoxin which is a highly basic protein may be combining with the more acidic phospholipid components of lipoproteins present in the plasma membrane of susceptible cells, possibly by formation of ionic complexes. The complexicity of lipoproteins and their particular orientation on the membrane of different cell types could account for the preferential effects shown by this cytotoxin. © 1969.