Tripartite motif-containing 28 (TRIM28)

Tripartite motif-containing 28 (TRIM28), also known as KRAB-associated protein-1 (KAP1) and TIF1β, is a multifunctional nuclear protein encoded by the *TRIM28* gene. It is a member of the tripartite motif family, characterized by an RBCC structure (RING finger, two B-boxes, and a coiled-coil region), a plant homeodomain (PHD), and a bromodomain. TRIM28 acts as a master scaffold and transcriptional corepressor, recruiting chromatin-modifying enzymes (e.g., SETDB1, HDACs) and heterochromatin protein 1 to silence genes and transposable elements, primarily via interaction with KRAB-ZFP transcription factors. It plays critical roles in gene silencing, embryonic stem cell pluripotency, cellular differentiation, DNA damage repair, and the establishment of viral latency. Dysregulation or overexpression of TRIM28 is associated with tumor proliferation, poor prognosis in several cancers, and it is being explored as a therapeutic target, though its central role in cell physiology raises safety concerns about broad inhibition[1][2][3][4].

Other names

KRAB-associated protein-1KAP1Transcription intermediary factor 1-betaTIF1βKRIP1TRIM28

Assembly of epigenetic silencing complexes (via interactions with KRAB-ZFPs and chromatin modifiers); Recruitment of histone methyltransferases (e.g., SETDB1) and histone deacetylases for gene silencing; Repression of retrotransposon and viral transcription by chromatin condensation; Regulation of DNA repair pathways via phosphorylation (e.g., ATM-mediated)