KRAB box; The KRAB domain (or Kruppel-associated box) is present in about a third of zinc finger proteins containing C2H2 fingers. The KRAB domain is found to be involved in protein-protein interactions. The KRAB domain is generally encoded by two exons. The regions coded by the two exons are known as KRAB-A and KRAB-B. The A box plays an important role in repression by binding to corepressors, while the B box is thought to enhance this repression brought about by the A box. KRAB-containing proteins are thought to have critical functions in cell proliferation and differentiation, apoptosis and neoplastic transformation.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|..
gi 1621574582   5 SVTFADVAVNFTKEEWTLLDPAQRNLYRDVMLENSRNLAFID 46
Cdd:pfam01352   1 SVTFEDVAVDFTQEEWALLDPAQRNLYRDVMLENYRNLVSLG 42

Zinc-finger double domain;

                          10        20
                  ....*....|....*....|..
gi 1621574582 378 HIRSHTGEKPYKCKTCGKDFAK 399
Cdd:pfam13465   5 HMRTHTGEKPYKCPECGKSFKS 26

KRAB box; The KRAB domain (or Kruppel-associated box) is present in about a third of zinc finger proteins containing C2H2 fingers. The KRAB domain is found to be involved in protein-protein interactions. The KRAB domain is generally encoded by two exons. The regions coded by the two exons are known as KRAB-A and KRAB-B. The A box plays an important role in repression by binding to corepressors, while the B box is thought to enhance this repression brought about by the A box. KRAB-containing proteins are thought to have critical functions in cell proliferation and differentiation, apoptosis and neoplastic transformation.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|..
gi 1621574582   5 SVTFADVAVNFTKEEWTLLDPAQRNLYRDVMLENSRNLAFID 46
Cdd:pfam01352   1 SVTFEDVAVDFTQEEWALLDPAQRNLYRDVMLENYRNLVSLG 42

KRAB (Kruppel-associated box) domain -A box; The KRAB domain is a transcription repression module, found in a subgroup of the zinc finger proteins (ZFPs) of the C2H2 family, KRAB-ZFPs. KRAB-ZFPs comprise the largest group of transcriptional regulators in mammals, and are only found in tetrapods. These proteins have been shown to play important roles in cell differentiation and organ development, and in regulating viral replication and transcription. A KRAB domain may consist of an A-box, or of an A-box plus either a B-box, a divergent B-box (b), or a C-box. Only the A-box is included in this model. The A-box is needed for repression, the B- and C- boxes are not. KRAB-ZFPs have one or two KRAB domains at their amino-terminal end, and multiple C2H2 zinc finger motifs at their C-termini. Some KRAB-ZFPs also contain a SCAN domain which mediates homo- and hetero-oligomerization. The KRAB domain is a protein-protein interaction module which represses transcription through recruiting corepressors. A key mechanism appears to be the following: KRAB-AFPs tethered to DNA recruit, via their KRAB domain, the repressor KAP1 (KRAB-associated protein-1, also known as transcription intermediary factor 1 beta , KRAB-A interacting protein , and tripartite motif protein 28). The KAP1/ KRAB-AFP complex in turn recruits the heterochromatin protein 1 (HP1) family, and other chromatin modulating proteins, leading to transcriptional repression through heterochromatin formation.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|
gi 1621574582   6 VTFADVAVNFTKEEWTLLDPAQRNLYRDVMLENSRNLAFI 45
Cdd:cd07765     1 VTFEDVAVYFSQEEWELLDPAQRDLYRDVMLENYENLVSL 40

Zinc-finger double domain;

                          10        20
                  ....*....|....*....|..
gi 1621574582 378 HIRSHTGEKPYKCKTCGKDFAK 399
Cdd:pfam13465   5 HMRTHTGEKPYKCPECGKSFKS 26

KRAB box; The KRAB domain (or Kruppel-associated box) is present in about a third of zinc finger proteins containing C2H2 fingers. The KRAB domain is found to be involved in protein-protein interactions. The KRAB domain is generally encoded by two exons. The regions coded by the two exons are known as KRAB-A and KRAB-B. The A box plays an important role in repression by binding to corepressors, while the B box is thought to enhance this repression brought about by the A box. KRAB-containing proteins are thought to have critical functions in cell proliferation and differentiation, apoptosis and neoplastic transformation.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|..
gi 1621574582   5 SVTFADVAVNFTKEEWTLLDPAQRNLYRDVMLENSRNLAFID 46
Cdd:pfam01352   1 SVTFEDVAVDFTQEEWALLDPAQRNLYRDVMLENYRNLVSLG 42

KRAB (Kruppel-associated box) domain -A box; The KRAB domain is a transcription repression module, found in a subgroup of the zinc finger proteins (ZFPs) of the C2H2 family, KRAB-ZFPs. KRAB-ZFPs comprise the largest group of transcriptional regulators in mammals, and are only found in tetrapods. These proteins have been shown to play important roles in cell differentiation and organ development, and in regulating viral replication and transcription. A KRAB domain may consist of an A-box, or of an A-box plus either a B-box, a divergent B-box (b), or a C-box. Only the A-box is included in this model. The A-box is needed for repression, the B- and C- boxes are not. KRAB-ZFPs have one or two KRAB domains at their amino-terminal end, and multiple C2H2 zinc finger motifs at their C-termini. Some KRAB-ZFPs also contain a SCAN domain which mediates homo- and hetero-oligomerization. The KRAB domain is a protein-protein interaction module which represses transcription through recruiting corepressors. A key mechanism appears to be the following: KRAB-AFPs tethered to DNA recruit, via their KRAB domain, the repressor KAP1 (KRAB-associated protein-1, also known as transcription intermediary factor 1 beta , KRAB-A interacting protein , and tripartite motif protein 28). The KAP1/ KRAB-AFP complex in turn recruits the heterochromatin protein 1 (HP1) family, and other chromatin modulating proteins, leading to transcriptional repression through heterochromatin formation.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|
gi 1621574582   6 VTFADVAVNFTKEEWTLLDPAQRNLYRDVMLENSRNLAFI 45
Cdd:cd07765     1 VTFEDVAVYFSQEEWELLDPAQRDLYRDVMLENYENLVSL 40

Zinc-finger double domain;

                          10        20
                  ....*....|....*....|..
gi 1621574582 378 HIRSHTGEKPYKCKTCGKDFAK 399
Cdd:pfam13465   5 HMRTHTGEKPYKCPECGKSFKS 26

Zinc finger, C2H2 type; The C2H2 zinc finger is the classical zinc finger domain. The two conserved cysteines and histidines co-ordinate a zinc ion. The following pattern describes the zinc finger. #-X-C-X(1-5)-C-X3-#-X5-#-X2-H-X(3-6)-[H/C] Where X can be any amino acid, and numbers in brackets indicate the number of residues. The positions marked # are those that are important for the stable fold of the zinc finger. The final position can be either his or cys. The C2H2 zinc finger is composed of two short beta strands followed by an alpha helix. The amino terminal part of the helix binds the major groove in DNA binding zinc fingers. The accepted consensus binding sequence for Sp1 is usually defined by the asymmetric hexanucleotide core GGGCGG but this sequence does not include, among others, the GAG (=CTC) repeat that constitutes a high-affinity site for Sp1 binding to the wt1 promoter.

                          10        20
                  ....*....|....*....|...
gi 1621574582 304 HKCPECGRAFFYQSFLMRHMKIH 326
Cdd:pfam00096   1 YKCPDCGKSFSRKSNLKRHLRTH 23