Helix-loop-helix DNA-binding domain;

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gi 1337931611  33 RSTHNELEKNRRAHLRLCLERLKVLIPLGPDCTRHTTLGLLNKAKAHIKKLE 84
Cdd:pfam00010   2 REAHNERERRRRDRINDAFDELRELLPTLPPDKKLSKAEILRLAIEYIKHLQ 53

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in the Mad family; Members of the Mad family (Mad1, Mxi, Mad3, and Mad4) bear the bHLHzip domain (also known as basic-helix-loop-helix-leucine-zipper or bHLH-LZ domain), which mediates heterodimerization to Max and the sequence-specific DNA binding ability to E-box DNA. Mad family proteins can repress transcription at the E-box through their interaction with co-repressors. Mad family proteins antagonize Myc function in transactivation and transformation and they are growth/tumor suppressors. The developmental phenotypes of the individual Mad family member knockout mice are relatively mild- all these mice have been shown to be viable and normal.

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gi 1337931611  33 RSTHNELEKNRRAHLRLCLERLKVLIPLGPDCTRHTTLGLLNKAKAHIKKLEEAERKSQHQLENLEREQRFLKRRL 108
Cdd:cd11401     1 RSTHNELEKNRRAHLRLCLERLKELVPLGPDATRHTTLSLLTKAKAYIKNLEDKEKRQRQQKEQLRREQRELKRRL 76

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in Max-associated protein 4 (Mad4) and similar proteins; Mad4, also termed Max dimerization protein 4, or Max dimerizer 4 (MXD4), or Class C basic helix-loop-helix protein 12 (bHLHc12), or Max-interacting transcriptional repressor MAD4, is a bHLHZip Max-interacting transcriptional repressor that suppresses c-myc dependent transformation and is expressed during neural and epidermal differentiation. It is regulated by a transcriptional repressor complex that contains Miz-1 and c-Myc.

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gi 1337931611  32 NRSTHNELEKNRRAHLRLCLERLKVLIPLGPDCTRHTTLGLLNKAKAHIKKLEEAERKSQHQLENLEREQRFLKRRLEQL 111
Cdd:cd18929     2 NRSSHNELEKHRRAKLRLYLEQLKQLVPLGPDSTRHTTLSLLKRAKMHIKKLEEQDRKALNIKEQLQREHRYLKRRLEQL 81

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in Max-binding protein Mnt and similar proteins; Mnt, also termed Class D basic helix-loop-helix protein 3 (bHLHd3), or Myc antagonist MNT, or protein ROX, is a bHLHZip transcriptional repressor that binds DNA as a heterodimer with MAX. It binds to the canonical E box sequence 5'-CACGTG-3' and, with higher affinity, to 5'-CACGCG-3'. Mnt has an important role as an antagonist and regulator of Myc activities and it is a potential tumor suppressor. Mnt is ubiquitously expressed. Mnt-deficient mice shown to exhibit early postnatal lethality.

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gi 1337931611  32 NRSTHNELEKNRRAHLRLCLERLKVLIPLGPDcTRHTTLGLLNKAKAHIKKLEEAERKSQHQLENLEREQRFLKRRL 108
Cdd:cd11402     2 TREVHNKLEKNRRAHLKECFETLKRQIPNLDD-KKTSNLNILRSALRYIQILKRKEKEYEHEMERLAREKIALQQRL 77

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in the Myc family; The Myc family is a member of the bHLHzip family of transcription factors that play important roles in the control of normal cell proliferation, growth, survival and differentiation. All Myc isoforms contain two independently functioning polypeptide chain regions: N-terminal transactivating residues and a C-terminal bHLHzip segment. The bHLHzip family of bHLH transcription factors are characterized by a highly conserved N-terminal basic region that may bind DNA at a consensus hexanucleotide sequence known as the E-box (CANNTG) followed by HLH and leucine zipper motifs that may interact with other proteins to form homo- and heterodimers. Myc heterodimerizes with Max enabling specific binding to E-box DNA sequences in the promoters of target genes. The Myc proto-oncoprotein family includes at least five different functional members: c-, N-, L-, S- and B-Myc (which is lacking the bHLH domain).

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gi 1337931611  33 RSTHNELEKNRRAHLRLCLERLKVLIPLGPDCTRHTTLGLLNKAKAHIKKLEEAERKSQHQLENLEREQRFLKRRLEQL 111
Cdd:cd11400     2 RRLHNVLERQRRNDLKNSFEKLRDLVPELADNEKASKVVILKKATEYIKQLQQEEKKLEKEKDKLKARNEQLRKKLERL 80

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in L-Myc and similar proteins; L-Myc, also termed Class E basic helix-loop-helix protein 38 (bHLHe38), or protein L-Myc-1, or V-myc myelocytomatosis viral oncogene homolog, is a bHLHZip oncoprotein belonging to the Myc oncogene protein family. It binds DNA as a heterodimer with MAX. L-Myc is co-expressed with another Myc family member and has weaker transformation/transactivation activities. L-Myc knockout mouse did not exhibit any phenotypic abnormalities.

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gi 1337931611  30 TANRSTHNELEKNRRAHLRLCLERLKVLIPLGPDCTRHTTLGLLNKAKAHIKKLEEAERKSQHQLENLEREQRFLKRRLE 109
Cdd:cd11457     5 VAKRKNHNFLERKRRNDLRSRFLALRDEVPGLASCSKTPKVVILSKATEYLRGLVSAERRMAAEKRQLKSRQQQLLRRIA 84

                  ....
gi 1337931611 110 QLQG 113
Cdd:cd11457    85 QLKG 88

basic Helix Loop Helix (bHLH) domain superfamily; bHLH proteins are transcriptional regulators that are found in organisms from yeast to humans. Members of the bHLH superfamily have two highly conserved and functionally distinct regions. The basic part is at the amino end of the bHLH that may bind DNA to a consensus hexanucleotide sequence known as the E box (CANNTG). Different families of bHLH proteins recognize different E-box consensus sequences. At the carboxyl-terminal end of the region is the HLH region that interacts with other proteins to form homo- and heterodimers. bHLH proteins function as a diverse set of regulatory factors because they recognize different DNA sequences and dimerize with different proteins. The bHLH proteins can be divided to cell-type specific and widely expressed proteins. The cell-type specific members of bHLH superfamily are involved in cell-fate determination and act in neurogenesis, cardiogenesis, myogenesis, and hematopoiesis.

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gi 1337931611  40 EKNRRAHLRLCLERLKVLIPLGPDCTRHTTLGLLNKAKAHIKKLEE 85
Cdd:cd00083     1 ERRRRDKINDAFEELKRLLPELPDSKKLSKASILQKAVEYIRELQS 46

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in N-Myc and similar proteins; N-Myc, also termed Class E basic helix-loop-helix protein 37 (bHLHe37), is a bHLHZip proto-oncogene protein that positively regulates the transcription of MYCNOS in neuroblastoma cells. It is also essential during embryonic development. N-Myc has a critical role in regulating the switch between proliferation and differentiation of progenitor cells. It binds DNA as a heterodimer with MAX. The family also includes S-Myc, encoded by rat or mouse intronless myc gene, which has apoptosis-inducing activity.

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gi 1337931611  33 RSTHNELEKNRRAHLRLCLERLKVLIPLGPDCTRHTTLGLLNKAKAHIKKLEEAERKSQHQLENLEREQRFLKRRLEQLQ 112
Cdd:cd11456     6 RRNHNILERQRRNDLRSSFLTLRDHVPELVKNEKAAKVVILKKATEYVHSLQAEEQKLLLEKEKLQARQQQLLKKIEQAR 85