PlantTFDB
Plant Transcription Factor Database
v4.0
Previous version: v1.0, v2.0, v3.0
Medicago truncatula
bHLH Family
Species TF ID Description
Medtr0007s0330.1bHLH family protein
Medtr0007s0330.2bHLH family protein
Medtr0007s0380.1bHLH family protein
Medtr0011s0210.1bHLH family protein
Medtr0011s0260.1bHLH family protein
Medtr0194s0050.1bHLH family protein
Medtr0246s0020.1bHLH family protein
Medtr0246s0020.2bHLH family protein
Medtr0246s0050.1bHLH family protein
Medtr0250s0040.1bHLH family protein
Medtr0632s0010.1bHLH family protein
Medtr1g017350.1bHLH family protein
Medtr1g017350.2bHLH family protein
Medtr1g017350.3bHLH family protein
Medtr1g017350.4bHLH family protein
Medtr1g017350.5bHLH family protein
Medtr1g018090.1bHLH family protein
Medtr1g018090.2bHLH family protein
Medtr1g019240.1bHLH family protein
Medtr1g028470.1bHLH family protein
Medtr1g032600.1bHLH family protein
Medtr1g032600.2bHLH family protein
Medtr1g040435.1bHLH family protein
Medtr1g043430.1bHLH family protein
Medtr1g048330.1bHLH family protein
Medtr1g048710.1bHLH family protein
Medtr1g048720.1bHLH family protein
Medtr1g048720.2bHLH family protein
Medtr1g048720.3bHLH family protein
Medtr1g048720.4bHLH family protein
Medtr1g048750.1bHLH family protein
Medtr1g052470.1bHLH family protein
Medtr1g056700.1bHLH family protein
Medtr1g059270.1bHLH family protein
Medtr1g059270.2bHLH family protein
Medtr1g060700.1bHLH family protein
Medtr1g069155.1bHLH family protein
Medtr1g070870.1bHLH family protein
Medtr1g070870.2bHLH family protein
Medtr1g072320.1bHLH family protein
Medtr1g072530.1bHLH family protein
Medtr1g072530.2bHLH family protein
Medtr1g077640.1bHLH family protein
Medtr1g080890.1bHLH family protein
Medtr1g082480.1bHLH family protein
Medtr1g082480.2bHLH family protein
Medtr1g084980.1bHLH family protein
Medtr1g084980.2bHLH family protein
Medtr1g093750.1bHLH family protein
Medtr1g094085.1bHLH family protein
Medtr1g102370.1bHLH family protein
Medtr1g102380.1bHLH family protein
Medtr1g106460.1bHLH family protein
Medtr1g106460.2bHLH family protein
Medtr1g106470.1bHLH family protein
Medtr1g106470.2bHLH family protein
Medtr1g106480.1bHLH family protein
Medtr1g112680.1bHLH family protein
Medtr1g116790.1bHLH family protein
Medtr2g010450.1bHLH family protein
Medtr2g011070.1bHLH family protein
Medtr2g013920.1bHLH family protein
Medtr2g015890.1bHLH family protein
Medtr2g015890.2bHLH family protein
Medtr2g015890.7bHLH family protein
Medtr2g022280.1bHLH family protein
Medtr2g038040.1bHLH family protein
Medtr2g039620.1bHLH family protein
Medtr2g039620.2bHLH family protein
Medtr2g067000.1bHLH family protein
Medtr2g081040.1bHLH family protein
Medtr2g081820.1bHLH family protein
Medtr2g081820.2bHLH family protein
Medtr2g082640.1bHLH family protein
Medtr2g084280.1bHLH family protein
Medtr2g089000.1bHLH family protein
Medtr2g089070.1bHLH family protein
Medtr2g090425.1bHLH family protein
Medtr2g090440.1bHLH family protein
Medtr2g090480.1bHLH family protein
Medtr2g090515.1bHLH family protein
Medtr2g091190.1bHLH family protein
Medtr2g098310.1bHLH family protein
Medtr2g098310.2bHLH family protein
Medtr2g098310.4bHLH family protein
Medtr2g098310.5bHLH family protein
Medtr2g100490.1bHLH family protein
Medtr2g101520.1bHLH family protein
Medtr2g104490.1bHLH family protein
Medtr2g104490.2bHLH family protein
Medtr2g104500.1bHLH family protein
Medtr2g104530.1bHLH family protein
Medtr2g104550.1bHLH family protein
Medtr2g104560.1bHLH family protein
Medtr2g104590.1bHLH family protein
Medtr2g104650.1bHLH family protein
Medtr3g027650.1bHLH family protein
Medtr3g027650.2bHLH family protein
Medtr3g027650.3bHLH family protein
Medtr3g028520.1bHLH family protein
Medtr3g028520.2bHLH family protein
Medtr3g030700.1bHLH family protein
Medtr3g070970.1bHLH family protein
Medtr3g090850.1bHLH family protein
Medtr3g099620.1bHLH family protein
Medtr3g101810.1bHLH family protein
Medtr3g103030.1bHLH family protein
Medtr3g104100.1bHLH family protein
Medtr3g111290.1bHLH family protein
Medtr3g112170.1bHLH family protein
Medtr3g116770.1bHLH family protein
Medtr3g116770.2bHLH family protein
Medtr3g438070.1bHLH family protein
Medtr3g449770.1bHLH family protein
Medtr3g498695.1bHLH family protein
Medtr3g498695.2bHLH family protein
Medtr3g498825.1bHLH family protein
Medtr4g009110.1bHLH family protein
Medtr4g009540.1bHLH family protein
Medtr4g009540.2bHLH family protein
Medtr4g033295.1bHLH family protein
Medtr4g033295.2bHLH family protein
Medtr4g033295.3bHLH family protein
Medtr4g057270.1bHLH family protein
Medtr4g065870.1bHLH family protein
Medtr4g065870.2bHLH family protein
Medtr4g065870.3bHLH family protein
Medtr4g066380.1bHLH family protein
Medtr4g066460.1bHLH family protein
Medtr4g067010.1bHLH family protein
Medtr4g070320.1bHLH family protein
Medtr4g075480.1bHLH family protein
Medtr4g075480.2bHLH family protein
Medtr4g075480.3bHLH family protein
Medtr4g078350.1bHLH family protein
Medtr4g079760.1bHLH family protein
Medtr4g081370.1bHLH family protein
Medtr4g081370.2bHLH family protein
Medtr4g081980.1bHLH family protein
Medtr4g085660.1bHLH family protein
Medtr4g085700.1bHLH family protein
Medtr4g087300.1bHLH family protein
Medtr4g087300.2bHLH family protein
Medtr4g087300.3bHLH family protein
Medtr4g087920.1bHLH family protein
Medtr4g091910.1bHLH family protein
Medtr4g091990.1bHLH family protein
Medtr4g092700.1bHLH family protein
Medtr4g094758.1bHLH family protein
Medtr4g094762.1bHLH family protein
Medtr4g097920.1bHLH family protein
Medtr4g097920.2bHLH family protein
Medtr4g097940.1bHLH family protein
Medtr4g097950.1bHLH family protein
Medtr4g098035.1bHLH family protein
Medtr4g107320.1bHLH family protein
Medtr4g108360.1bHLH family protein
Medtr4g110040.1bHLH family protein
Medtr4g110040.2bHLH family protein
Medtr4g110040.3bHLH family protein
Medtr4g118830.1bHLH family protein
Medtr4g131160.1bHLH family protein
Medtr4g131160.2bHLH family protein
Medtr5g005110.1bHLH family protein
Medtr5g005110.2bHLH family protein
Medtr5g014520.1bHLH family protein
Medtr5g014560.1bHLH family protein
Medtr5g014600.1bHLH family protein
Medtr5g014640.1bHLH family protein
Medtr5g017040.1bHLH family protein
Medtr5g017210.1bHLH family protein
Medtr5g030430.1bHLH family protein
Medtr5g030770.1bHLH family protein
Medtr5g030770.2bHLH family protein
Medtr5g032375.1bHLH family protein
Medtr5g037250.1bHLH family protein
Medtr5g039180.1bHLH family protein
Medtr5g046160.1bHLH family protein
Medtr5g048350.1bHLH family protein
Medtr5g048350.2bHLH family protein
Medtr5g048860.1bHLH family protein
Medtr5g048860.10bHLH family protein
Medtr5g048860.2bHLH family protein
Medtr5g048860.3bHLH family protein
Medtr5g048860.4bHLH family protein
Medtr5g048860.5bHLH family protein
Medtr5g048860.6bHLH family protein
Medtr5g048860.7bHLH family protein
Medtr5g048860.8bHLH family protein
Medtr5g048860.9bHLH family protein
Medtr5g064950.1bHLH family protein
Medtr5g064950.2bHLH family protein
Medtr5g066080.1bHLH family protein
Medtr5g079500.1bHLH family protein
Medtr6g011670.1bHLH family protein
Medtr6g047550.1bHLH family protein
Medtr6g047570.1bHLH family protein
Medtr6g052280.1bHLH family protein
Medtr6g084120.1bHLH family protein
Medtr6g488100.1bHLH family protein
Medtr6g488100.2bHLH family protein
Medtr6g488100.3bHLH family protein
Medtr6g488100.4bHLH family protein
Medtr7g010120.1bHLH family protein
Medtr7g017320.1bHLH family protein
Medtr7g017320.2bHLH family protein
Medtr7g039110.1bHLH family protein
Medtr7g053410.1bHLH family protein
Medtr7g053410.2bHLH family protein
Medtr7g059260.1bHLH family protein
Medtr7g069590.1bHLH family protein
Medtr7g076840.1bHLH family protein
Medtr7g080780.1bHLH family protein
Medtr7g080780.2bHLH family protein
Medtr7g083900.1bHLH family protein
Medtr7g083900.2bHLH family protein
Medtr7g083900.3bHLH family protein
Medtr7g089400.1bHLH family protein
Medtr7g090410.1bHLH family protein
Medtr7g092510.1bHLH family protein
Medtr7g092540.1bHLH family protein
Medtr7g092540.2bHLH family protein
Medtr7g096350.1bHLH family protein
Medtr7g096350.2bHLH family protein
Medtr7g096650.3bHLH family protein
Medtr7g099540.1bHLH family protein
Medtr7g099540.2bHLH family protein
Medtr7g110810.1bHLH family protein
Medtr7g111320.1bHLH family protein
Medtr7g113830.1bHLH family protein
Medtr7g117670.1bHLH family protein
Medtr8g009010.1bHLH family protein
Medtr8g009020.1bHLH family protein
Medtr8g012290.1bHLH family protein
Medtr8g012290.2bHLH family protein
Medtr8g015450.1bHLH family protein
Medtr8g015450.2bHLH family protein
Medtr8g015450.3bHLH family protein
Medtr8g015450.4bHLH family protein
Medtr8g024210.1bHLH family protein
Medtr8g024770.1bHLH family protein
Medtr8g024790.1bHLH family protein
Medtr8g027495.1bHLH family protein
Medtr8g032210.1bHLH family protein
Medtr8g036235.1bHLH family protein
Medtr8g036235.2bHLH family protein
Medtr8g062240.1bHLH family protein
Medtr8g064700.1bHLH family protein
Medtr8g065740.1bHLH family protein
Medtr8g066770.1bHLH family protein
Medtr8g067280.1bHLH family protein
Medtr8g069740.1bHLH family protein
Medtr8g093500.1bHLH family protein
Medtr8g098275.1bHLH family protein
Medtr8g098275.2bHLH family protein
Medtr8g098275.3bHLH family protein
Medtr8g099880.1bHLH family protein
Medtr8g466800.1bHLH family protein
Medtr8g466800.2bHLH family protein
bHLH Family Introduction

The basic/helix-loop-helix (bHLH) proteins are a superfamily of transcription factors that have been well characterized in nonplant eukaryotes, especially in mammalian systems, in which considerable structural, functional, and phylogenetic analyses have been performed. The data indicate that bHLH proteins are important regulatory components in transcriptional networks in these systems, controlling a diversity of processes from cell proliferation to cell lineage establishment.

This family is defined by the bHLH signature domain, which consists of 60 amino acids with two functionally distinct regions. The basic region, located at the N-terminal end of the domain, is involved in DNA binding and consists of 15 amino acids with a high number of basic residues. The HLH region, at the C-terminal end, functions as a dimerization domain and is constituted mainly of hydrophobic residues that form two amphipathic -helices separated by a loop region of variable sequence and length. Outside of the conserved bHLH domain, these proteins exhibit considerable sequence divergence. Cocrystal structural analysis has shown that the interaction between the HLH regions of two separate polypeptides leads to the formation of homodimers and/or heterodimers and that the basic region of each partner binds to half of the DNA recognition sequence. Some bHLH proteins form homodimers or restrict their heterodimerization activity to closely related members of the family. On the other hand, some can form heterodimers with one or several different partners.

The core DNA sequence motif recognized by the bHLH proteins is a consensus hexanucleotide sequence known as the E-box (5'-CANNTG-3'). There are different types of E-boxes, depending on the identity of the two central bases. One of the most common is the palindromic G-box (5'-CACGTG-3'). Certain conserved amino acids within the basic region of the protein provide recognition of the core consensus site, whereas other residues in the domain dictate specificity for a given type of E-box . In addition, flanking nucleotides outside of the hexanucleotide core have been shown to play a role in binding specificity, and there is evidence that a loop residue in the protein plays a role in DNA binding through elements that lie outside of the core recognition sequence.

Toledo-Ortiz G, Huq E, Quail PH.
The Arabidopsis basic/helix-loop-helix transcription factor family.
Plant Cell. 2003 Aug;15(8):1749-70
PMID: 12897250