Conserved Protein Domain Family

cd00083: bHLH_SF 
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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.
PSSM-Id: 381392
Aligned: 78 rows
Threshold Bit Score: 32.4921
Created: 1-Nov-2000
Updated: 2-Oct-2020
Aligned Rows:
DNA bindingdimer interface
Conserved site includes 6 residues -Click on image for an interactive view with Cn3D
Feature 1:DNA binding site [nucleic acid binding site]
  • Comment:The N-terminal basic region of bHLH mediates high-affinity DNA-binding to specific hexanucleotide sequences
  • Structure:1MDY; Mus musculus myoD basic region binds DNA, contacts at 4A
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  • Citation:PMID 8181063
  • Structure:2YPA; Homo sapiens SCL:E47bHLH heterodimer binds DNA, contacts at 4A.
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  • Structure:2QL2; Mus musculus NeuroD1 and E47 heterodimer binds DNA, contacts at 4A.
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Sequence Alignment
Format: Row Display: Color Bits: Type Selection:
Feature 1        ## #    #                                 ##                
1MDY_B        14 ERRRLSKVNEAFETLKRsTSsnpn---------------qrlPKVEILRNAIRYIEGLQA 58  house mouse
1AM9_A        14 EKRYRSSINDKIIELKDlVVgte----------------aklNKSAVLRKAIDYIRFLQH 57  human
Q9NX45       210 EKLRRERIKYCCEQLRTlLPyvkg---------------rknDAASVLEATVDYVKYIRE 254 human
Q9UH92       138 EQKRRDAIKRGYDDLQTiVPtcqqqdf--------sigsqklSKAIVLQKTIDYIQFLHK 189 human
Q9NP71       658 EQKRRFNIKLGFDTLHGlVStlsaq------------pslkvSKATTLQKTAEYILMLQQ 705 human
CBN76935     279 EQKRSLKISQRIEDLRRmLSqfgv--------------dvkaSKSAVLSEATDYIAHLQR 324 Ectocarpus siliculosus
OEU14159     372 EQQRSSKISTQIKELREvLSecnv--------------pfkpNKYSILLKVVEYIKQLQS 417 Fragilariopsis cylindrus CCMP1102
PRP75940      79 EQRRRQKINEKINELREiLNype----------------gvqNKAVVLQAAVEHIKNLKT 122 Planoprotostelium fungivorum
KZT43449      85 EKRRREKINTALSELRTlVPakfarqnahdaddpesrqadkeFKLEILERTVAYVKHLSD 144 Sistotremastrum suecicum HHB10207 ss-3
XP_005644417  67 EKRRRDRIHEGIVMLREvVVpqk----------------ekeDQAAFLRSAAEYIRQLQT 110 Coccomyxa subellipsoidea C-169

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