Histones and histone phosphorylation during quail myogenesis in vitro.

Cultured quail myoblasts were labelled with 32Pi and nuclear proteins extracted before and after myoblast fusion. Histones H1, H4 and the H1-H2B-H2A complex were all phosphorylated in proliferating prefusion cultures, while histone phosphorylation was absent in B1-arrested postfusion cultures except for minor phosphorylation of the H3-H2B-H2A complex. Postfused cultures were distinguished by the appearance of the histone-like protein whch migrated slightly faster than H1. Histone phosphorylation is therefore correlated with cell proliferation, while the appearance of the new histone-like protein is associated with G1 arrest and the absence of cell division.