TIF1β Background Information
TIF1∫, for transcriptional intermediary factor 1-beta, also designated KAP1(for KRAB-associated protein 1), TF1∫ and TRIM28 (for tripartif motif-containing 28), is a member of the tripartif motif family characterized by three zinc-binding domains, a RING finger, B-boxes and a coiled-coil domain (1,2,4). Like TIF1å, TIF1∫ contains both a Cys/His PHD (plant homeodomain) finger and bromodomain that form a cooperative unit required for transcriptional repression (3,5). TIF1∫ mediates transcriptional control by interaction with the Kruppel-associated box (KRAB) repression domain found in many transcription factors and by binding DNA through its zinc finger (3,6). The human TIF1∫ gene maps to human chromosome 19q13.4 and encodes an 835 amino acid nuclear protein (3,4).
