Invitrogen™ TRIM28 Polyclonal Antibody

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.