Interaction of phleomycin with soluble cytoplasmic proteins from HeLa S-3 cells

Abstract

Summary Phleomycin, an antibiotic obtained from Streptomyces verticillus, interacts with the high speed (100 000 g) supernatant fraction of HeLa and other cells. The reaction, which is temperature-independent and therefore physical in nature, occurs above a concentration of 0.2 mg/ml phleomycin, producing an amorphous white precipitate of proteins. It does not seem to involve the co-precipitation of phleomycin in the manner of vinblastine (VLB) precipitates. Comparisons are drawn between the precipitation phenomena observed with these two anti-mitotic agents on a number of parameters. Although neither brings down specific proteins, their precipitates have some distinctly different components as well as many similar ones, including microtubule protein. There is no evidence that the interaction of phleomycin with CS proteins is involved in its anti-mitotic activity as compared with vinblastine. Furthermore, the related antibiotic bleomycin, which is equally as effective as phleomycin anti-mitotically, does not precipitate CS proteins.