Figure 1.

Inheritance of histone modification patterns. Two models for the maintenance of histone modifications are presented, which may apply in different organisms and cellular contexts. (A) Modified histones are evenly distributed between the daughter strands during replication, where they act as a template for further recruitment of histone modifiers to reestablish the original epigenetic state. (B) During replication, modified histones are rapidly replaced by unmethylated histones. Epigenetic modifiers (such as TrxG and PcG) remain stably associated with their binding elements (or other factors) during the progression of the replication fork and re-establish the histone modification patterns onto the newly deposited histones.