Mitotic post-translational modifications of histones promote chromatin compaction in vitro

As histones undergo major changes in their post-translational modifications during mitotic entry, we speculated that the spectrum of cell cycle-specific histone modifications might contribute to chromosome compaction during mitosis. To test this hypothesis, we isolated core histones from interphase and mitotic cells and reconstituted chromatin with them. We used mass spectrometry to show that key post-translational modifications remained intact during our isolation procedure.