In nondividing cells, histone H1(0) is synthesized and deposited onto chromatin without accompanying phosphorylation

The phosphorylation of H1 histone subfractions was measured in mouse neuroblastoma cells stopped from dividing by three treatments that block cell division: 5 mM butyrate, 2% dimethyl sulfoxide, and serum withdrawal. H1 histone phosphorylation decreased in response to all three treatments, but the response differed in its timing and its extent for the different H 1 subfractions. The different decreases in phosphorylation correlated well with the differential decreases in biosynthesis of the individual H1 subfractions; however, an exception to this parallel decrease in synthesis and phosphorylation was observed in the case of histone H1(0). Phosphorylation of H1(0) was absent in each of the three treatments after 2 days, despite the continued synthesis and deposit of H1(0) on the chromatin. Thus, despite the fact that H1(0) was being synthesized and that the other newly synthesized H1 subfractions were phosphorylated at this time, the phosphorylation of H1(0) became uncoupled from its synthesis after prolonged treatments blocking cell division.