Phosphorylation of distinct regions of f1 histone. Relationship to the cell cycle.

Abstract

The phosphorylation of different amino acids in distinct regions of fl histone was studied in highly synchronized Chinese hamster cell populations (line CHO). The purified, 32P-labeled fl histone was bisected into NH,-terminal and COOH-terminal fragments with N-bromosuccinimide. Tryptic phosphopeptides from these fragments were resolved using sequential high voltage electrophoretic steps on paper. No phosphorylation was observed in early G,-arrested cells. Interphase phosphorylation began in late G, in the COOH-terminal portion of the molecule on serine. This event continued throughout S phase and persisted into mitosis. However, in mitosis additional phosphorylation was observed in the Cell Cycle-specific Phosphorylation of Histone fl