[Sequence of activation of template biosynthesis in normal and transformed human cells after synchronization by a...

The sequence of matrix biosyntheses of DNA, RNA and various proteins in normal and transformed human fibroblasts in the first mitotic cycle after synchronization of cells by double thymidine block was studied. Two important regularities of synthesis of acid-soluble histone-like and acid-insoluble proteins in normal and transformed cells were established. In normal fibroblasts, the synthesis of both acid-soluble and acid-insoluble proteins is minimal before DNA replication and maximal in the G2-phase; that in transformed cells is maximal after removal of the thymidine block and decreased in the G2-phase. In normal fibroblasts, the synthesis of acid-insoluble proteins is maximal before, while that of acid-soluble ones--after the maximum of DNA synthesis. In transformed cells the situation is opposite. RNA synthesis in normal and transformed cells is stimulated at the end of the G2-phase. In normal cells, protein synthesis is coupled with the activation of RNA synthesis, whereas in transformed fibroblasts protein synthesis occurs, in all probability, in the next mitotic cycle. These differences are especially well-pronounced in the expression of some LMG proteins. It is concluded that in transformed cells the regulatory control over the coupling of matrix biosyntheses is impaired.