摘要：

The distribution of unphosphorylated and phosphorylated isoforms of linker histone H1 protein was examined during the cell cycle of HeLa cells by quantitative light and electron microscopic immunocytochemistry. Immunolabeling with a monoclonal antibody directed against the globular domain of H1 (anti-H1), which recognized predominantly unphosphorylated H1, and a polyclonal antibody directed against hyperphosphorylated H1 (anti-H1P) revealed that: (1) H1 immunolabeling was lowest at the start of S phase (S_S), and then increased progressively during the middle (S_i) to end of S phase (S_e), mitosis (M) and telophase (T) to reach the highest level in G1 phase, at which time there was a sudden reduction in H1 immunolabeling before the start of S phase; (2) H1P immunolabeling paralleled this progressive increase, but only until M phase, after which it abruptly disappeared and was virtually absent in G1; (3)

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