The KRAB (Kruppel-associated box) domain is about 45 amino acids in length and is a transcriptional repression domain found in numerous transcription factors. There have been identified over 220 KRAB-zinc finger protein (KRAB-ZFP) genes in the human genome. These proteins functionally repress transcription via specific interactions with KAP-1 (KRAB-associated protein 1). KAP-1 is an 835 amino acid polypeptide that contains a RING finger, B boxes, and a PHD finger. KAP-1 has been shown to form complexes with KRAB-domain transcription factors and increase the efficiency with which they mediate repression. KAP-1 has also been shown to directly interact with HP1 (heterochromatin protein 1) and KRAZ1 (Kruppel-associated box-containing zinc finger protein 1). KAP-1 directly targets KRAZ1 to the foci of centromeric heterochromatin containing HP1alpha, thus helping to regulate transcriptional repression. Studies have shown that KAP-1 mutants with the ability to bind KRAB but unable to bind HP1 leads to random distribution of KRAZ1 and strong transcriptional activation.
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Protein Aliases: E3 SUMO-protein ligase TRIM28; KAP-1; KRAB [Kruppel-associated box domain]-associated protein 1; KRAB-A-interacting protein; KRAB-associated protein 1; KRAB-interacting p; KRAB-interacting protein 1; KRIP-1; Nuclear corepressor KAP-1; protein phosphatase 1, regulatory subunit 157; RING finger protein 96; RING-type E3 ubiquitin transferase TIF1-beta; tif1 beta; TIF1-beta; Transcription intermediary factor 1-beta; transcriptional intermediary factor 1, beta; transcriptional intermediary factor 1-beta; tripartite motif; tripartite motif protein 28; Tripartite motif-containing protein 28
Gene Aliases: AA408787; KAP-1; KAP1; KRIP-1; Krip1; MommeD9; PPP1R157; RNF96; TF1B; TIF1B; Tif1beta; TRIM28