Characterization of chromatin-bound erythrocyte histone V (f2c). Synthesis, acetylation, and phosphorylation

Synthesis and enzymatic modification of histone V was 1 order of magnitude lower in mature gander erythrocytes as compared with immature enriched cells hwich were capable of DNA synthesis. Application of shallow, linear gradient chromatography was used to demonstrate qualitative changes as well. This technique permitted the separation of newly synthesized and phosphorylated histone V from older, less phosphorylated molecules but did not discriminate between acetylated species. The most easily eluted fractions were those most recently synthesized, acetylated, and phosphorylated. While lysine chased into the other subfractions of histone V, phosphate did not, indicating a dephosphorylation step in the immature cells. Acetylation of histone V which occurs at a very low level was closely related to its synthesis. No differences in molecular weights or amino acid compositions were apparent, and behavior on polyacrylamide gels was similar to whole histone V. It is proposed that phosphorylation of histone V may play an important role in the modulation of the effect of histone V in immature cells on condensation and template restriction of chromatin which occurs in the terminal stages of differentiation of the avian erythroid cells.