KRAB_domain
Krüppel associated box
Protein domain
The Krüppel associated box (KRAB) domain is a category of transcriptional repression domains present in approximately 400 human zinc finger protein-based transcription factors (KRAB zinc finger proteins).[1] The KRAB domain typically consists of about 75 amino acid residues, while the minimal repression module is approximately 45 amino acid residues.[2] It is predicted to function through protein-protein interactions via two amphipathic helices. The most prominent interacting protein is called TRIM28 initially visualized as SMP1,[3] cloned as KAP1[4] and TIF1-beta.[5] Substitutions for the conserved residues abolish repression.
Over 10 independently encoded KRAB domains have been shown to be effective repressors of transcription, suggesting this activity to be a common property of the domain. KRAB domains can be fused with dCas9 CRISPR tools to form even stronger repressors.[6]