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. 2011 Aug 18;6(8):e23747. doi: 10.1371/journal.pone.0023747

Figure 5. Proposed model of MAGE-KAP1 interactions.

Figure 5

KAP1 performs diverse functions by serving as a molecular scaffold that binds multiple proteins which allow it to regulate chromatin environments. KAP1 has an N terminal RING-B-box coiled-coil (RBCC) domain that binds to the KRAB domains of KZNFs, which target KAP1 to specific DNA sequences through their zinc finger DNA binding motifs. KAP1 mediates localized compaction of euchromatin to heterochromatin that is necessary for suppression of specific gene transcription, and that is associated with chromatin modifications including histone de-acetylation, histone 3 tri-methylation on K9, and HP1 binding to both DNA and histones. In some cases, MAGE expression enhances KAP1 E3 ubiquitin ligase activity, resulting in KZNF ubiquitination and degradation, thereby de-repressing KZNF mediated gene repression, shown as (-). In other cases, MAGE enhances KZNF and KAP1 localization to specific gene loci, shown as (+) (After A. Ivanov [22]).