PHD finger found in transcription intermediary factor 1-alpha (TIF1-alpha)
TIF1-alpha, also termed tripartite motif-containing protein 24 (TRIM24), or E3 ubiquitin-protein ligase TRIM24, or RING finger protein 82, belongs to the TRIM/RBCC protein family. It interacts specifically and in a ligand-dependent manner with the ligand binding domain (LBD) of several nuclear receptors (NRs), including retinoid X (RXR), retinoic acid (RAR), vitamin D3 (VDR), estrogen (ER), and progesterone (PR) receptors. It also associates with heterochromatin-associated factors HP1alpha, MOD1 (HP1beta) and MOD2 (HP1gamma), as well as vertebrate Kruppel-type (C2H2) zinc finger proteins that contain transcriptional silencing domain KRAB. TIF1-alpha is a ligand-dependent co-repressor of retinoic acid receptor (RAR) that interacts with multiple nuclear receptors in vitro via an LXXLL motif, and further acts as a gatekeeper of liver carcinogenesis. It also functions as an E3-ubiquitin ligase targeting p53 and is broadly associated with chromatin silencing. Moreover, it is a chromatin regulator that recognizes specific, combinatorial histone modifications through its C-terminal plant homeodomain (PHD)-Bromodomain (Bromo) region. In addition, it interacts with chromatin and estrogen receptor to activate estrogen-dependent genes associated with cellular proliferation and tumor development. TIF1-alpha contains an N-terminal RBCC (RING finger, B-box zinc-fingers, coiled-coil), a plant homeodomain (PHD) finger, followed by a bromodomain in the C-terminal region.
Jiyao W et al.(2023). "The conserved domain database in 2023.",