The synthesis of acidic chromosomal proteins during the cell cycle of HeLa S-3 cells. I. The accelerated accumulation of acidic residual nuclear protein before the initiation of DNA replication
The synthesis and accumulation of acidic proteins in the tightly bound residual nuclear fraction goes on throughout the cell cycle of continuously dividing populations of HeLa S-3 cells; however, during late G(1) there is an increased rate of synthesis and accumulation of these proteins which precedes the onset of DNA synthesis. Unlike that of the histones, whose synthesis is tightly coupled to DNA replication, the synthesis of acidic residual nuclear proteins is insensitive to inhibitors of DNA synthesis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of acidic residual nuclear proteins shows different profiles during the G(1), S, and G(2) phases of the cell cycle. These results suggest that, in contrast to histones whose synthesis appears to be highly regulated, the acidic residual proteins may have a regulatory function in the control of cell proliferation in continuously dividing mammalian cells.