Fig. 3.

(Color online) Model of epigenetic suppression of transposable elements. KRAB-containing ZFPs are recruited to transposable elements, which then recruits the docking platform TRIM28 protein. This complex then recruits various co-repressor complexes, including (but not limited to) DNMTs, CoREST, SETDB1, PRC1, PRC2, HDACs, and NuRD. Other non-KRAB C2H2 ZFPs may also recruit co-repressors to TEs, particularly RYBP and YY1. These actions result in the gain of the repressive histone marks H3K27me3 and H3K9me3, the gain of variant histone H3.3 and DNA methylation to silence expression, along with the loss of the activatory H3K4me3 and Histone acetylation. Ultimately, many more epigenetic repressive mechanisms are likely to be involved in the suppression of TEs