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. Author manuscript; available in PMC: 2012 Oct 22.
Published in final edited form as: Nat Rev Genet. 2010 May 5;11(6):439–446. doi: 10.1038/nrg2765

Figure 2. Establishment of silencing and barrier activity.

Figure 2

a,b|Silencing elements (S) recruit specific transcription factors (TF), which in turn recruit chromatin remodellers (CR) and histone-modifying enzymes (HM) that cooperate to modify chromatin and create binding sites in nucleosomes for repressor proteins. c,d|The binding and spreading of the repressor proteins (R) along the chromatin fibre results in the formation of a silenced heterochromatic domain. Barrier elements (B) bind a distinct set of transcription factors that recruit enzyme complexes, which modify nucleosomes with ‘active’ histone marks and evict nucleosomes. This creates a discontinuity in the chromatin fibre and thereby restricts the spread of repressor proteins.