Figure 8. Proposed models for the targeting of Cbx-PRC1 to chromatin.
(A) The Cbx7-PRC1 and Cbx8-PRC1 complexes are targeted to chromatin by co-recognition of H3K27me3 and DNA. The Cbx7- and Cbx8-PRC1 complexes are guided to genomic loci by the CD interaction with H3K27me3. The interaction triggers conformational changes of the Cbx7- and Cbx8-PRC1 complexes and induces the CD-ATL cassette interaction with DNA. Multivalent engagement of DNA and H3K27me3 by the CD-ATL cassette stabilizes the Cbx7- and Cbx8-PRC1 complexes at chromatin. (B) Molecular mechanisms for the targeting of Cbx2-PRC1, Cbx4-PRC1, and Cbx6-PRC1 complexes to chromatin remain unknown.