helix loop helix domain;

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|
gi 5453734      59 NELEKHRRAKLRLYLEQLKQLVPLGPDSTRHTTLSLLKRAKVHIKKLEEQ 108
Cdd:smart00353   1 NARERRRRRKINEAFDELRSLLPTLPKNKKLSKAEILRLAIEYIKSLQEE 50

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.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 5453734   55 RSSHNELEKHRRAKLRLYLEQLKQLVPLGPDSTRHTTLSLLKRAKVHIKKLEEQDRRALSIKEQLQQEHRFLKRRL 130
Cdd:cd11401   1 RSTHNELEKNRRAHLRLCLERLKELVPLGPDATRHTTLSLLTKAKAYIKNLEDKEKRQRQQKEQLRREQRELKRRL 76

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in protein Max-associated protein 1 (Mad1) and similar proteins; Mad1, also termed Max dimerization protein 1 (MXD1), or Max dimerizer 1, or protein MAD, is a bHLHZip transcriptional repressor that binds with MAX to form a sequence-specific DNA-binding protein complex which recognizes the core sequence 5'-CAC[GA]TG-3'. It thus antagonizes MYC transcriptional activity by competing for MAX.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 5453734   54 NRSSHNELEKHRRAKLRLYLEQLKQLVPLGPDSTRHTTLSLLKRAKVHIKKLEEQDRRALSIKEQLQQEHRFLKRRLEQL 133
Cdd:cd18931   1 SRSTHNEMEKNRRAHLRLCLEKLKMLVPLGPESNRHTTLSLLMKAKLHIKKLEDSDRKAVHQIDQLQREQRHLKRQLEKL 80

helix loop helix domain;

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|
gi 5453734      59 NELEKHRRAKLRLYLEQLKQLVPLGPDSTRHTTLSLLKRAKVHIKKLEEQ 108
Cdd:smart00353   1 NARERRRRRKINEAFDELRSLLPTLPKNKKLSKAEILRLAIEYIKSLQEE 50

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).

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 5453734   55 RSSHNELEKHRRAKLRLYLEQLKQLVPLGPDSTRHTTLSLLKRAKVHIKKLEEQDRRALSIKEQLQQEHRFLKRRLEQL 133
Cdd:cd11400   2 RRLHNVLERQRRNDLKNSFEKLRDLVPELADNEKASKVVILKKATEYIKQLQQEEKKLEKEKDKLKARNEQLRKKLERL 80

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in c-Myc and similar proteins; c-Myc, also termed Myc proto-oncogene protein, or Class E basic helix-loop-helix protein 39 (bHLHe39), or transcription factor p64, a bHLHZip proto-oncogene protein that functions as a transcription factor, which binds DNA in a non-specific manner, yet also specifically recognizes the core sequence 5'-CAC[GA]TG-3'. It activates the transcription of growth-related genes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 5453734   55 RSSHNELEKHRRAKLRLYLEQLKQLVPLGPDSTRHTTLSLLKRAKVHIKKLEEQDRRALSIKEQLQQEHRFLKRRLEQL 133
Cdd:cd11458   6 RRTHNVLERQRRNELKLSFFALRDQIPEVANNEKAPKVVILKKATEYILSMQADEQRLISEKEQLRRRREQLKHRLEQL 84

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.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*.
gi 5453734   62 EKHRRAKLRLYLEQLKQLVPLGPDSTRHTTLSLLKRAKVHIKKLEE 107
Cdd:cd00083   1 ERRRRDKINDAFEELKRLLPELPDSKKLSKASILQKAVEYIRELQS 46

basic helix-loop-helix-Per-ARNT-Sim (bHLH-PAS) domain found in aryl hydrocarbon receptor nuclear translocator (ARNT) family; The ARNT family of bHLH-PAS transcription regulators includes ARNT, ARNT-like proteins (ARNTL and ARNTL2), and Drosophila melanogaster protein cycle. They act as the heterodimeric partner for bHLH-PAS proteins such as aryl hydrocarbon receptor (AhR), hypoxia-inducible factor (HIF), and single-minded (SIM). These bHLH-PAS transcription complexes are involved in transcriptional responses to xenobiotic, hypoxia, and developmental pathways. Heterodimerization of bHLH-PAS proteins with ARNT is mediated by contacts between both the bHLH and the tandem PAS domains. ARNT use bHLH and/or PAS domains to interact with several transcriptional coactivators. It is required for activity of the aryl hydrocarbon (dioxin) receptor. ARNTL, also termed Basic-helix-loop-helix-PAS protein MOP3, or brain and muscle ARNT-like 1 (BMAL1), or Class E basic helix-loop-helix protein 5 (bHLHe5), or member of PAS protein 3, or PAS domain-containing protein 3 (PASD3), or bHLH-PAS protein JAP3, is a member of the bHLH-PAS transcription factor family that forms heterodimers with another bHLH-PAS protein, CLOCK (circadian locomotor output cycle kaput), which regulates circadian rhythm. ARNTL-CLOCK heterodimer complex activates transcription from E-box (CANNTG) elements found in the promoter of circadian responsive genes. ARNTL is highly homologous to ARNT. ARNTL2, also termed Basic-helix-loop-helix-PAS protein MOP9, or brain and muscle ARNT-like 2 (BMAL2), or CYCLE-like factor (CLIF), or Class E basic helix-loop-helix protein 6 (bHLHe6), or member of PAS protein 9, or PAS domain-containing protein 9 (PASD9), is a neuronal bHLH-PAS transcriptional factor, regulating cell cycle progression and preventing cell death, whose sustained expression might ensure brain neuron survival. It also plays important roles in tumor angiogenesis. Protein cycle, also termed brain and muscle ARNT-like 1 (BMAL1), or MOP3, is a putative bHLH-PAS transcription factor involved in the generation of biological rhythms in Drosophila. It activates cycling transcription of Period (PER) and Timeless (TIM) by binding to the E-box (5'-CACGTG-3') present in their promoters.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|..
gi 5453734   55 RSSHNELEKHRRAKLRLYLEQLKQLVPL-GPDSTRHTTLSLLKRAKVHIKKL 105
Cdd:cd11437   2 RSNHSEIEKRRRDKMNAYIQELSALVPAcNAMSRKLDKLTVLRMAVQHLKSL 53

basic helix-loop-helix (bHLH) domain found in the spermatogenesis- and oogenesis-specific basic helix-loop-helix-containing protein (SOHLH) family and similar proteins; The SOHLH family includes two bHLH transcription factors, SOHLH1 and SOHLH2. They are specifically in spermatogonia and oocytes and essential for early spermatogonial and oocyte differentiation. The family also includes transcription factor-like 5 protein (TCFL5) and similar proteins. TCFL5, also termed Cha transcription factor, or HPV-16 E2-binding protein 1 (E2BP-1), is a bHLH transcription factor that plays a crucial role in spermatogenesis. It regulates cell proliferation or differentiation of cells through binding to a specific DNA sequence like other bHLH molecules.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....*
gi 5453734   54 NRSSHNELEKHRRAKLRLYLEQLKQLVPLGPDSTRHTTlsLLKRAKVHIKKLEEQ 108
Cdd:cd19683   2 SRERHNAKERQRRERIKIACDQLRKLVPGCSRKTDKAT--VFEFTVAYIKFLREK 54

basic helix-loop-helix-Per-ARNT-Sim (bHLH-PAS) domain family; bHLH-PAS domain has been found in a large group of bHLH transcription regulators that are involved in gene expression responding to environmental change and controlling aspects of neural development, including proteins from aryl hydrocarbon receptor nuclear translocator (ARNT) family, hypoxia-inducible factor (HIF) family, aryl hydrocarbon receptor (AhR) family, neuronal PAS domain-containing protein (NPAS) family, Circadian locomotor output cycles protein kaput (CLOCK)-like family, and single-minded (SIM) family. bHLH-PAS transcriptional regulatory factors have a bHLH DNA-binding domain followed by two PAS domains and a C-terminal activation or repression domain. bHLH-PAS family members can be divided into class I and class II based on their dimerization partner. bHLH-PAS class I factors include AhR, HIF and SIM. The best characterized bHLH-PAS Class II protein is the ubiquitous ARNT. Some members of bHLH-PAS family act as transcriptional coactivators (such as NCoA) that lack the ability to dimerize and bind DNA.

                        10        20        30
                ....*....|....*....|....*....|....*
gi 5453734   55 RSSHNELEKHRRAKLRLYLEQLKQLVPLGPDSTRH 89
Cdd:cd11391   1 REKSREAAKKRRDKENAEISELASLLPLPPAVGSK 35

basic helix-loop-helix-Per-ARNT-Sim (bHLH-PAS) domain found in Drosophila melanogaster protein cycle and similar proteins; Protein cycle, also termed brain and muscle ARNT-like 1 (BMAL1), or MOP3, is a putative bHLH-PAS transcription factor involved in the generation of biological rhythms in Drosophila. It activates cycling transcription of Period (PER) and Timeless (TIM) by binding to the E-box (5'-CACGTG-3') present in their promoters.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|..
gi 5453734   55 RSSHNELEKHRRAKLRLYLEQLKQLVPLGPDSTRH-TTLSLLKRAKVHIKKL 105
Cdd:cd19726   2 RQNHSEIEKRRRDKMNTYITELSSMIPMCNAMSRKlDKLTVLRMAVQHMKTL 53

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana genes coding transcription factors and similar proteins; bHLH proteins are the second largest class of plant transcription factors that regulate transcription of genes that are involve in many essential physiological and developmental process. bHLH proteins are transcriptional regulators that are found in organisms from yeast to humans. The Arabidopsis bHLH proteins that have been characterized so far have roles in regulation of fruit dehiscence, cell development (carpel, anther and epidermal), phytochrome signaling, flavonoid biosynthesis, hormone signaling and stress responses.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|.
gi 5453734   58 HNELEKHRRAKLRLYLEQLKQLVplgPDSTRHTTLSLLKRAKVHIKKLEEQ 108
Cdd:cd11393   1 HSIAERKRREKINERIRALRSLV---PNGGKTDKASILDEAIEYIKFLQEQ 48

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in upstream stimulatory factor 1 (USF1) and similar proteins; USF1, also termed Class B basic helix-loop-helix protein 11 (bHLHb11), or major late transcription factor 1, is a bHLHzip transcription factor that binds to a symmetrical DNA sequence (E-boxes) (5'-CACGTG-3') that is found in a variety of viral and cellular promoters. It is ubiquitously expressed and involved in the transcription activation of various functional genes implicated in lipid and glucose metabolism, stress response, immune response, cell cycle control and tumour suppression. USF-1 recruits chromatin remodeling enzymes and interact with co-activators and the members of the transcription pre-initiation complex. Genetic polymorphisms of USF1 are associated with some metabolic and cardiovascular diseases, like diabetes, atherosclerosis, coronary artery calcifications and familial combined hyperlipidaemia (FCHL).

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 5453734   55 RSSHNELEKHRRAKLRLYLEQLKQLVplgPDSTRHTTLS------LLKRAKVHIKKLEEQDRR 111
Cdd:cd18924   6 RAQHNEVERRRRDKINNWIVQLSKII---PDCSMESTKSgqskggILSKACDYIQELRQSNHR 65

basic helix-loop-helix-Per-ARNT-Sim (bHLH-PAS) domain found in aryl hydrocarbon receptor nuclear translocator-like protein 2 (ARNTL2) and similar proteins; ARNTL2, also termed Basic-helix-loop-helix-PAS protein MOP9, or brain and muscle ARNT-like 2 (BMAL2), or CYCLE-like factor (CLIF), or Class E basic helix-loop-helix protein 6 (bHLHe6), or member of PAS protein 9, or PAS domain-containing protein 9 (PASD9), is a neuronal bHLH-PAS transcriptional factor, regulating cell cycle progression and preventing cell death, whose sustained expression might ensure brain neuron survival. It also plays important roles in tumor angiogenesis. ARNT-2 heterodimerize with other bHLH-PAS proteins such as aryl hydrocarbon receptor (AhR), hypoxia-inducible factor (HIF), and single-minded (SIM).

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 5453734   55 RSSHNELEKHRRAKLRLYLEQLKQLVP-LGPDSTRHTTLSLLKRAKVHIKKLE 106
Cdd:cd11469   2 REAHSQTEKRRRDKMNNLIEELSAMIPqCNPMARKLDKLTVLRMAVQHLKSLK 54