PHD finger found in transcription intermediary factor 1-beta (TIF1-beta)
TIF1-beta, also termed Kruppel-associated Box (KRAB)-associated protein 1 (KAP-1), or KRAB-interacting protein 1 (KRIP-1), or nuclear co-repressor KAP-1, or RING finger protein 96, or tripartite motif-containing protein 28 (TRIM28), or E3 SUMO-protein ligase TRIM28, acts as a nuclear co-repressor that plays a role in transcription and in DNA damage response. Upon DNA damage, the phosphorylation of KAP-1 on serine 824 by the ataxia telangiectasia-mutated (ATM) kinase enhances cell survival and facilitates chromatin relaxation and heterochromatic DNA repair. It also regulates CHD3 nucleosome remodeling during DNA double-strand break (DSB) response. Meanwhile, KAP-1 can be dephosphorylated by protein phosphatase PP4C in the DNA damage response. In addition, KAP-1 is a co-activator of the orphan nuclear receptor NGFI-B (or Nur77) and is involved in NGFI-B-dependent transcription. It is also a coiled-coil binding partner, substrate and activator of the c-Fes protein tyrosine kinase. TIF1-beta contains an N-terminal RBCC (RING finger, B-box zinc-fingers, coiled-coil), which can interact with KRAB zinc finger proteins (KRAB-ZFPs), MDM2, MM1, C/EBPbeta, and mediates homo- and heterodimerization, a plant homeodomain (PHD) finger followed by a bromodomain in the C-terminal region, which interact with SETDB1, Mi-2alpha and other proteins to form complexes with histone deacetylase or methyltransferase activity.
Jiyao W et al.(2023). "The conserved domain database in 2023.",