Helix-loop-helix DNA-binding domain;

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|
gi 4504573     66 CDMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQ 105
Cdd:pfam00010  14 DRINDAFDELRELLPTLPPDKKLSKAEILRLAIEYIKHLQ 53

basic helix-loop-helix (bHLH) domain found in the DNA-binding protein inhibitor (ID) family; The ID family includes a dominant negative group of helix-loop-helix (dnHLH) proteins, ID1-4, that are negative regulators of bHLH transcription factors. They contain the HLH-dimerization domain but lack the basic domain necessary for DNA-binding. ID proteins inhibit binding to DNA and transcriptional transactivation by heterodimerization with bHLH proteins. They also interact with many non-bHLH proteins in complex networks. ID proteins have been implicated in regulating gene expression as well as cell-cycle progression. Whereas ID-1, ID-2 and ID-3, are generally considered as tumor promoters, ID4 on the contrary has emerged as a tumor suppressor.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*.
gi 4504573   62 LCLQCDMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLA 107
Cdd:cd19684   2 DILNAEMQDCYSKLKELVPTIPQNKKVSKVEILQHVIDYILDLQLA 47

basic helix-loop-helix (bHLH) domain found in DNA-binding protein inhibitor ID1 and similar proteins; ID1, also termed Class B basic helix-loop-helix protein 24 (bHLHb24), or inhibitor of DNA binding 1, or inhibitor of differentiation 1, is a dominant negative helix-loop-helix (dnHLH) transcriptional regulator (lacking a basic DNA binding domain) which negatively regulates the bHLH transcription factors by forming heterodimers and inhibiting their DNA binding and transcriptional activity. ID1 interferes with centrosomal function. It has been implicated in the regulation of cell proliferation and differentiation in myogenesis, neurogenesis, and/or hematopoiesis.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*.
gi 4504573   67 DMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLALETHP 112
Cdd:cd19691   7 DMNGCYSRLKELVPTLPQNRKVSKVEILQHVIDYIWDLQVELDSGP 52

basic helix-loop-helix (bHLH) domain found in Drosophila melanogaster protein extra-macrochaetae and similar proteins; Extra-macrochaetae is a negative regulator of sensory organ development in Drosophila. It belongs to dominant negative group of helix-loop-helix (dnHLH) proteins, which lack a basic DNA-binding domain but can form heterodimers with other HLH proteins, thereby inhibiting DNA binding.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|.
gi 4504573   72 YSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLALETHP 112
Cdd:cd19695  12 LAKLRNLVPTLPKNRKVSKLELLQHVIDYIADLEEQLEDHP 52

helix loop helix domain;

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....
gi 4504573      67 DMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLALET 110
Cdd:smart00353  10 KINEAFDELRSLLPTLPKNKKLSKAEILRLAIEYIKSLQEELQK 53

basic helix-loop-helix (bHLH) domain found in achaete-scute complex-like (ASCL) family; The achaete-scute complex-like (ASCL, also known as achaete-scute complex homolog or ASH) family of bHLH transcription factors, ASCL1-5, have been implicated in cell fate specification and differentiation. They are critical for proper development of the nervous system. The deregulation of ASCL plays a key role in psychiatric and neurological disorders. ASCL-1, also termed Class A basic helix-loop-helix protein 46 (bHLHa46), or achaete-scute homolog 1 (ASH-1), or mammalian achaete-scute homolog 1 (Mash1), is a neural-specific bHLH transcription factor that is expressed in subsets of neural progenitors in both the central and peripheral nervous system. It plays a key role in neuronal differentiation and specification in the nervous system. ASCL-2, also termed achaete-scute homolog 2 (ASH-2), or Class A basic helix-loop-helix protein 45 (bHLHa45), or mammalian achaete-scute homolog 2 (Mash2), is a bHLH transcription factor that is involved in Schwann cell differentiation and control of proliferation in adult peripheral nerves. ASCL-3, also termed Class A basic helix-loop-helix protein 42 (bHLHa42), or bHLH transcriptional regulator Sgn-1, or achaete-scute homolog 3 (ASH-3), is a bHLH transcription factor specifically localized in the duct cells of the salivary glands. It may act as transcriptional repressor that inhibits myogenesis. The family also includes Drosophila melanogaster achaete-scute complex (AS-C) proteins, which consists of lethal of scute (also known as achaete-scute complex protein T3 or AST3), scute (also known as achaete-scute complex protein T4 or AST4), achaete (also known as achaete-scute complex protein T5 or AST5), and asense (also known as achaete-scute complex protein T8 or AST8). They are involved in the determination of the neuronal precursors in the peripheral nervous system and the central nervous system, as well as in sex determination and dosage compensation.

                        10        20        30
                ....*....|....*....|....*....|....*..
gi 4504573   69 NDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQ 105
Cdd:cd11418  17 NDAFDRLRQHVPYLKRRKKLSKVKTLRRAIEYIRHLQ 53

basic helix-loop-helix (bHLH) domain found in factor in the germline alpha (FIGLA) and similar proteins; FIGLA, also termed FIGalpha, or Class C basic helix-loop-helix protein 8 (bHLHc8), or folliculogenesis-specific basic helix-loop-helix protein, or transcription factor FIGa, is a germ-cell-specific bHLH transcription factor expressed abundantly in female and less so in male germ cells. It is essential for primordial follicle formation and expression of many genes required for folliculogenesis, fertilization and early embryonic survival. FIGLA knockout mice cannot form primordial follicles and lose oocytes rapidly after birth, whereas male gonads are unaffected.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|..
gi 4504573   68 MNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLALE 109
Cdd:cd11422  15 LNSGFSKLRRIVPLIPRDRKPSKVDTLKGATEYIRLLQRILE 56

basic helix-loop-helix (bHLH) domain found in Drosophila melanogaster helix loop helix protein 3B (dHLH3B) and similar proteins; Drosophila HLH3B is an uncharacterized bHLH transcription factor that belongs to the T-cell acute lymphocytic leukemia protein/ lymphoblastic leukemia-derived sequence (TAL/LYL) family.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*
gi 4504573   65 QCDMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLALE 109
Cdd:cd19708  13 QQNVNGAFAELRKLVPTHPPDKKLSKNEILRLAIKYIRLLSNVLE 57

basic helix-loop-helix (bHLH) domain found in T-cell acute lymphocytic leukemia protein/ lymphoblastic leukemia-derived sequence (TAL/LYL) family; The TAL/LYL family includes a group of bHLH transcription factors (TAL1, TAL2 and LYL1) implicated in T cell acute leukaemia. They act as mediators of T cell leukaemogenesis. TAL-1, also termed Class A basic helix-loop-helix protein 17 (bHLHa17), or stem cell protein (SCL), or T-cell leukemia/lymphoma protein 5, is a hematopoietic-specific bHLH transcription factor that functions in embryonic and adult hematopoiesis in vertebrates. It is also required for embryonic vascular remodeling. It acts as a regulator of erythroid differentiation and binds to regulatory regions of a large cohort of erythroid genes as part of a complex with GATA-1, LMO2 and Ldb1. TAL-2, also termed Class A basic helix-loop-helix protein 19 (bHLHa19), is a bHLH transcription factor essential for the normal brain development. Lyl-1, also termed Class A basic helix-loop-helix protein 18 (bHLHa18), or lymphoblastic leukemia-derived sequence 1, is a proto-oncogenic bHLH transcription factor that plays an important role in hematopoietic stem cell function and is required for the late stages of postnatal angiogenesis to limit the formation of new blood vessels, notably by regulating the activity of the small GTPase Rap1. LYL-1 deficiency induces a stress erythropoiesis.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*
gi 4504573   65 QCDMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLALE 109
Cdd:cd11413  13 QQNVNGAFAELRKLIPTHPPDKKLSKNEILRLAMKYIKFLEKILE 57

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
                ....*....|....*....|....*....|....*....|....*....|....
gi 4504573   67 DMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQ---LALETHPALLRQ 117
Cdd:cd11400  15 DLKNSFEKLRDLVPELADNEKASKVVILKKATEYIKQLQqeeKKLEKEKDKLKA 68

basic helix-loop-helix (bHLH) domain found in protein lyl-1 and similar proteins; Lyl-1, also termed Class A basic helix-loop-helix protein 18 (bHLHa18), or lymphoblastic leukemia-derived sequence 1, is a proto-oncogenic bHLH transcription factor involved in T-cell acute lymphoblastic leukemia. It plays an important role in hematopoietic stem cell function and is required for the late stages of postnatal angiogenesis to limit the formation of new blood vessels, notably by regulating the activity of the small GTPase Rap1. LYL-1 deficiency induces a stress erythropoiesis.

                        10        20        30
                ....*....|....*....|....*....|....*..
gi 4504573   65 QCDMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYI 101
Cdd:cd19705  18 QQNVNGAFAELRKLIPTHPPDKKLSKNEILRLAMKYI 54

basic helix-loop-helix (bHLH) domain found in Fer3-like protein (FERD3L), pancreas transcription factor 1 subunit alpha (PTF1A) and similar proteins; The family corresponds to a group of bHLH transcription factors, including FERD3L and PTF1A. FERD3L, also termed basic helix-loop-helix protein N-twist, or Class A basic helix-loop-helix protein 31 (bHLHa31), or nephew of atonal 3 (NATO3), or Neuronal twist (NTWIST), is expressed in the developing central nervous system (CNS). It regulates floor plate (FP) cells development. FP is a critical organizing center located at the ventral-most midline of the neural tube. FERD3L binds to the E-box and functions as inhibitor of transcription. PTF1A, also termed Class A basic helix-loop-helix protein 29 (bHLHa29), or pancreas-specific transcription factor 1a, or bHLH transcription factor p48, or p48 DNA-binding subunit of transcription factor PTF1 (PTF1-p48), is implicated in the cell fate determination in various organs. It binds to the E-box consensus sequence 5'-CANNTG-3' and plays a role in early and late pancreas development and differentiation.

                        10        20        30
                ....*....|....*....|....*....|....*....
gi 4504573   66 CDMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDL 104
Cdd:cd19686  14 RSINDAFDGLRRHIPTFPYEKRLSKVDTLRLAIQYINFL 52

basic helix-loop-helix (bHLH) domain found in achaete-scute-like proteins, ASCL3-5, and similar proteins; This subfamily includes three ASCL family of transcription factors, ASCL-3, ASCL-4 and ASCL-5. ASCL-3, also termed Class A basic helix-loop-helix protein 42 (bHLHa42), or bHLH transcriptional regulator Sgn-1, or achaete-scute homolog 3 (ASH-3), is specifically localized in the duct cells of the salivary glands. It may act as transcriptional repressor that inhibits myogenesis. ASCL-4, also termed Class A basic helix-loop-helix protein 44 (bHLHa44), or achaete-scute homolog 4 (ASH-4), or Hash4, may be involved in skin development. ASCL-5, also termed Class A basic helix-loop-helix protein 47 (bHLHa47), or achaete-scute homolog 5 (ASH-5), is an uncharacterized bHLH transcription factor that is close related to ASCL-3 and ASCL-4.

                        10        20        30
                ....*....|....*....|....*....|....*..
gi 4504573   69 NDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQ 105
Cdd:cd19724  17 NEGYARLRRHLPLENKDKRLSKVETLRAAIRYIKHLQ 53

basic helix-loop-helix (bHLH) domain found in protein atonal homologs ATOH1, ATOH7 and similar proteins; The family includes ATOH1 and ATOH7. ATOH1, also termed Class A basic helix-loop-helix protein 14 (bHLHa14), or helix-loop-helix protein hATH-1 (hATH1), or Math1, or Cath1, is a proneural bHLH transcription factor that is essential for inner ear hair cell differentiation. It dimerizes with E47 and activates E-box (CANNTG) dependent transcription. ATOH1 is a mammalian homolog of the Drosophila melanogaster gene atonal and mouse atonal homolog 1 (Math1). ATOH7, also termed Class A basic helix-loop-helix protein 13 (bHLHa13), or helix-loop-helix protein hATH-5 (hATH5), or Math5, is a bHLH transcription factor involved in the differentiation of retinal ganglion cells. The family also includes protein Amos (also termed absent MD neurons and olfactory sensilla protein, or reduced olfactory organs protein, or rough eye protein). It is a bHLH transcription factor that promotes multiple dendritic neuron formation in the Drosophila peripheral nervous system.

                        10        20        30
                ....*....|....*....|....*....|....*...
gi 4504573   68 MNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQ 105
Cdd:cd11430  16 LNRAFDQLRSVVPSIGNDKKLSKYETLQMAQIYIETLS 53

basic helix-loop-helix-orange (bHLH-O) domain found in HERP/HES-like family; The HERP/HES-like family includes bHLH-O transcriptional regulators that are related to the Drosophila hairy and Enhancer-of-split (HES) proteins. The HERP (HES-related repressor protein) subfamily proteins contain a basic helix-loop-helix (bHLH) domain with an invariant glycine residue in its basic region, an orange domain in the central region and YXXW sequence motif at its C-terminal region. Hairy and enhancer of split (HES)-related repressor protein (HERP) proteins (HEY1, HEY2 and HEYL) act as downstream effectors of Notch signaling. They are involved in cardiovascular development and have roles in somitogenesis, myogenesis and gliogenesis. Hairy and enhancer of split-related protein HELT is a transcriptional repressor expressed in the developing central nervous system. It binds preferentially to the canonical E box sequence 5'-CACGCG-3' and regulates neuronal differentiation and/or identity. Differentially expressed in chondrocytes proteins, DEC1 and DEC2, are widely expressed in both embryonic and adult tissues and have been implicated in apoptosis, cell proliferation, and circadian rhythms, as well as malignancy in various cancers. Drosophila melanogaster protein clockwork orange (Cwo) is also included in this subfamily. It is involved in the regulation of Drosophila circadian rhythms. It functions as both an activator and a repressor of clock gene expression. The HES subfamily proteins contain a basic helix-loop-helix (bHLH) domain with an invariant proline residue in its basic region, an orange domain in the central region and a conserved tetrapeptide motif, WRPW, at its C-terminal region. They form heterodimers or homodimers via their HLH domain and bind DNA to repress gene transcription that play an essential role in development of both compartment and boundary cells of the central nervous system.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....
gi 4504573   68 MNDCYSRLRRLVP---TIPPNKKVSKVEILQHVIDYILDLQLAL 108
Cdd:cd19685   9 INDKLNQLKELLPpnlSKQSRSKLSKAEILEMAITELRRLQQEV 52

basic helix-loop-helix (bHLH) domain found in achaete-scute-like protein 1 (ASCL-1) and similar proteins; ASCL-1, also termed Class A basic helix-loop-helix protein 46 (bHLHa46), or achaete-scute homolog 1 (ASH-1), or mammalian achaete scute homolog 1 (Mash1), is a neural-specific bHLH transcription factor that is expressed in subsets of neural progenitors in both the central and peripheral nervous system. It plays a key role in neuronal differentiation and specification in the nervous system.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*..
gi 4504573   68 MNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLALETHPAL 114
Cdd:cd19742  20 VNMGFATLREHVPNGAANKKMSKVETLRSAVEYIRALQQLLDEHDAV 66

basic helix-loop-helix (bHLH) domain found in achaete-scute-like protein 4 (ASCL-4) and similar proteins; ASCL-4, also termed Class A basic helix-loop-helix protein 44 (bHLHa44), or achaete-scute homolog 4 (ASH-4), or Hash4, is a bHLH transcriptional regulator that may be involved in skin development.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|..
gi 4504573   68 MNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLALE 109
Cdd:cd19746  23 VNEGYARLREHLPQELADKRLSKVETLRAAIDYIKHLQELLE 64

basic helix-loop-helix-orange (bHLH-O) domain found in hairy and enhancer of split (HES)-related repressor protein (HERP)-like family; The HERP-like family includes bHLH-O transcriptional regulators that are related to the Drosophila hairy and Enhancer-of-split proteins. They contain a basic helix-loop-helix (bHLH) domain with an invariant glycine residue in its basic region, an orange domain in the central region and YXXW sequence motif at its C-terminal region. HERP proteins (HEY1, HEY2 and HEYL) act as downstream effectors of Notch signaling. They are involved in cardiovascular development and have roles in somitogenesis, myogenesis and gliogenesis. Hairy and enhancer of split-related protein HELT is a transcriptional repressor expressed in the developing central nervous system. It binds preferentially to the canonical E box sequence 5'-CACGCG-3' and regulates neuronal differentiation and/or identity. Differentially expressed in chondrocytes proteins, DEC1 and DEC2, are widely expressed in both embryonic and adult tissues and have been implicated in apoptosis, cell proliferation, and circadian rhythms, as well as malignancy in various cancers. Drosophila melanogaster protein clockwork orange (Cwo) is also included in this family. It is involved in the regulation of Drosophila circadian rhythms. It functions as both an activator and a repressor of clock gene expression.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|.
gi 4504573   68 MNDCYSRLRRLVPT---IPPNKKVSKVEILQHVIDYILDLQ 105
Cdd:cd11389  12 INESLAELRRLVPEarkSKGSGKLEKAEILEMTLQHLKALQ 52

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in sterol regulatory element-binding protein (SREBP) family and similar proteins; The SREBP family includes SREBP1 and SREBP2, which are bHLHzip transcriptional activator of genes encoding proteins essential for cholesterol biosynthesis/uptake and fatty acid biosynthesis. SREBP1 and SREBP2 are principally found in the liver and in adipocytes and made up of an N-terminal transcription factor portion (composed of an activation domain, a bHLHzip domain, and a nuclear localization signal), a hydrophobic region containing two membrane spanning regions, and a C-terminal regulatory segment. They recognize a symmetric sterol regulatory element (TCACNCCAC) instead of E-box. The family also includes Saccharomyces cerevisiae transcription factor HMS1 (also termed high-copy MEP suppressor protein 1) and serine-rich protein TYE7. HMS1 is a putative bHLHzip transcription factor involved in exit from mitosis and pseudohyphal differentiation. TYE7, also termed basic-helix-loop-helix protein SGC1, is a putative bHLHzip transcription activator required for Ty1-mediated glycolytic gene expression. TYE7 N-terminal is extremely rich in serine residues. It binds DNA on E-box motifs, 5'-CANNTG-3'. TYE7 is not essential for growth.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 4504573   68 MNDCYSRLRRLVPT---------------IPPNKKVSKVEILQHVIDYILDLQ 105
Cdd:cd11395  18 LNTKIERLRDAIPSlrspegksddgglggLAPTTKLSKATILTKAIEYIRHLE 70

basic helix-loop-helix-orange (bHLH-O) domain found in hairy and enhancer of split (HES)-related repressor protein (HERP) family; HERP (also called Hey/Hesr/HRT/CHF/gridlock) proteins corresponds to a family of bHLH-O transcriptional repressors that are related to the Drosophila hairy and Enhancer-of-split proteins and act as downstream effectors of Notch signaling. They contain a basic helix-loop-helix (bHLH) domain with an invariant glycine residue in its basic region, an orange domain in the central region and YXXW sequence motif at its C-terminal region. HERP proteins are involved in cardiovascular development and have roles in somitogenesis, myogenesis and gliogenesis.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|.
gi 4504573   68 MNDCYSRLRRLVPTI---PPNKKVSKVEILQHVIDYILDLQ 105
Cdd:cd11407  16 INNSLAELRRLVPTAfekQGSAKLEKAEILQMTVDHLKMLH 56

basic helix-loop-helix (bHLH) domain found in Fer3-like protein (FERD3L) and similar proteins; FERD3L, also termed basic helix-loop-helix protein N-twist, or Class A basic helix-loop-helix protein 31 (bHLHa31), or nephew of atonal 3 (NATO3), or Neuronal twist (NTWIST), is a bHLH transcription factor expressed in the developing central nervous system (CNS). It regulates floor plate (FP) cells development. FP is a critical organizing center located at the ventral-most midline of the neural tube. FERD3L binds to the E-box and functions as inhibitor of transcription.

                        10        20        30
                ....*....|....*....|....*....|....*
gi 4504573   67 DMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYI 101
Cdd:cd11415  23 NLNEAFDKLRKKVPTFAYEKRLSRIETLRLAIVYI 57

basic helix-loop-helix (bHLH) domain found in protein atonal homolog 8 (ATOH8) and similar proteins; ATOH8, also termed Class A basic helix-loop-helix protein 21 (bHLHa21), or helix-loop-helix protein hATH-6 (hATH6), is a bHLH shear-stress-responsive transcription factor expressed in activated satellite cells and proliferating myoblasts of human skeletal muscle tissue. It regulates endothelial cell proliferation, migration and tube-like structures formation. ATOH8 binds a palindromic (canonical) core consensus DNA sequence 5'-CANNTG- 3' known as an E-box element, possibly as a heterodimer with other bHLH proteins.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|..
gi 4504573   72 YSRLRRLVPTIPPNKKVSKVEILQHVIDYILDL-QLALETHP 112
Cdd:cd11421  27 FEALRKAVPSYSYNQKLSKLAILRIACSYILALaRLADLDYS 68

basic helix-loop-helix (bHLH) domain found in Drosophila melanogaster protein Amos and similar proteins; Amos, also termed absent MD neurons and olfactory sensilla protein, or reduced olfactory organs protein, or rough eye protein, is a bHLH transcription factor that promotes multiple dendritic neuron formation in the Drosophila peripheral nervous system.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|..
gi 4504573   68 MNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQLALE 109
Cdd:cd19715  23 LNVAFDKLRDVVPSLGDDRKLSKYETLQMAQSYITALKELLS 64

basic helix-loop-helix (bHLH) domain found in achaete-scute-like protein 5 (ASCL-5) and similar proteins; ASCL-5, also termed Class A basic helix-loop-helix protein 47 (bHLHa47), or achaete-scute homolog 5 (ASH-5), is an uncharacterized bHLH transcription factor that belongs to AS-C (achaete, scute, lethal of scute, and asense) family.

                        10        20        30
                ....*....|....*....|....*....|....*...
gi 4504573   68 MNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYILDLQ 105
Cdd:cd19747  21 VNEGYARLRDHLPGAMAEKRLSKVETLRAAIRYIKYLQ 58

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.

                        10        20        30
                ....*....|....*....|....*....|....*.
gi 4504573   70 DCYSRLRRLVPTIPpNKKVSKVEILQHVIDYILDLQ 105
Cdd:cd11402  19 ECFETLKRQIPNLD-DKKTSNLNILRSALRYIQILK 53

basic Helix-Loop-Helix-zipper (bHLHzip) domain found in sterol regulatory element-binding protein (SREBP) family; The SREBP family includes SREBP1 and SREBP2, which are bHLHzip transcriptional activator of genes encoding proteins essential for cholesterol biosynthesis/uptake and fatty acid biosynthesis. SREBP1 and SREBP2 are principally found in the liver and in adipocytes and made up of an N-terminal transcription factor portion (composed of an activation domain, a bHLHzip domain, and a nuclear localization signal), a hydrophobic region containing two membrane spanning regions, and a C-terminal regulatory segment. They recognize a symmetric sterol regulatory element (TCACNCCAC) instead of E-box.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|
gi 4504573   66 CDMNDCYSRLRRLVptIPPNKKVSKVEILQHVIDYILDLQ 105
Cdd:cd11394  19 SSINDRIIELKDLV--VGPDAKMNKSAVLRKAIDYIRYLQ 56

basic helix-loop-helix (bHLH) domain found in Caenorhabditis elegans Helix-loop-helix protein 13 (HLH13) and similar proteins; Caenorhabditis elegans HLH13, also termed Fer3-like protein, or nephew of atonal 3, is a bHLH transcription factor that plays a role in the negative regulation of exit from L1 arrest and dauer diapause dependent on IIS signaling (insulin and insulin-like growth factor (IGF) signaling).

                        10        20        30
                ....*....|....*....|....*....|....*.
gi 4504573   66 CDMNDCYSRLRRLVPTIPPNKKVSKVEILQHVIDYI 101
Cdd:cd11416  18 LSINSAFEELRCHVPTFPYEKRLSKIDTLRLAIAYI 53

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana protein aborted microspores (AMS) and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as AMS, ICE1 and SCREAM2. AMS, also termed AtbHLH21, or EN 48, plays a crucial role in tapetum development and it is required for male fertility and pollen differentiation. ICE1, also termed inducer of CBF expression 1, or AtbHLH116, or EN 45, or SCREAM, acts as a transcriptional activator that regulates the cold-induced transcription of CBF/DREB1 genes. It binds specifically to the MYC recognition sites (5'-CANNTG-3') found in the CBF3/DREB1A promoter. SCREAM2, also termed AtbHLH33, or EN 44, mediates stomatal differentiation in the epidermis probably by controlling successive roles of SPCH, MUTE, and FAMA.

                        10        20        30
                ....*....|....*....|....*....|....*...
gi 4504573   68 MNDCYSRLRRLVPTIppnKKVSKVEILQHVIDYILDLQ 105
Cdd:cd11443  14 LNDRLYMLRSVVPKI---TKMDRASILGDAIDYVKELL 48

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana protein transparent testa 8 (TT8) and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as TT8, EGL1, and GL3. TT8, also termed AtbHLH42, or EN 32, is involved in the control of flavonoid pigmentation and plays a key role in regulating leucoanthocyanidin reductase (BANYULS) and dihydroflavonol-4-reductase (DFR). EGL1, also termed AtbHLH2, or EN 30, or AtMYC146, or protein enhancer of GLABRA 3, is involved in epidermal cell fate specification and regulates negatively stomata formation but promotes trichome formation. GL3, also termed AtbHLH1, or AtMYC6, or protein shapeshifter, or EN 31, is involved in epidermal cell fate specification. It regulates negatively stomata formation, but, in association with TTG1 and MYB0/GL1, promotes trichome formation, branching and endoreplication.

                        10        20        30
                ....*....|....*....|....*....|....*...
gi 4504573   68 MNDCYSRLRRLVPTIppnKKVSKVEILQHVIDYILDLQ 105
Cdd:cd11451  17 LNERFITLRSMVPFV---TKMDKVSILGDAIEYLKQLQ 51