PlantTFDB
Plant Transcription Factor Database
v4.0
Previous version: v1.0, v2.0, v3.0
Sisymbrium irio
bHLH Family
Species TF ID Description
676703688bHLH family protein
676705534bHLH family protein
676708010bHLH family protein
676708044bHLH family protein
676708342bHLH family protein
676709010bHLH family protein
676709566bHLH family protein
676710046bHLH family protein
676710062bHLH family protein
676710064bHLH family protein
676710066bHLH family protein
676710080bHLH family protein
676710090bHLH family protein
676710092bHLH family protein
676710094bHLH family protein
676710624bHLH family protein
676710680bHLH family protein
676711192bHLH family protein
676711650bHLH family protein
676713048bHLH family protein
676713052bHLH family protein
676713246bHLH family protein
676714754bHLH family protein
676714772bHLH family protein
676715348bHLH family protein
676715510bHLH family protein
676718060bHLH family protein
676718210bHLH family protein
676719256bHLH family protein
676719304bHLH family protein
676719646bHLH family protein
676719664bHLH family protein
676720270bHLH family protein
676720272bHLH family protein
676720536bHLH family protein
676720656bHLH family protein
676720924bHLH family protein
676721078bHLH family protein
676721218bHLH family protein
676721930bHLH family protein
676723124bHLH family protein
676723262bHLH family protein
676723328bHLH family protein
676723366bHLH family protein
676723368bHLH family protein
676723376bHLH family protein
676727278bHLH family protein
676727814bHLH family protein
676728310bHLH family protein
676728718bHLH family protein
676729458bHLH family protein
676729730bHLH family protein
676729892bHLH family protein
676731456bHLH family protein
676732396bHLH family protein
676732794bHLH family protein
676733176bHLH family protein
676733448bHLH family protein
676734484bHLH family protein
676734722bHLH family protein
676734790bHLH family protein
676734824bHLH family protein
676735582bHLH family protein
676737798bHLH family protein
676738388bHLH family protein
676738748bHLH family protein
676738810bHLH family protein
676739564bHLH family protein
676739666bHLH family protein
676741004bHLH family protein
676742304bHLH family protein
676742308bHLH family protein
676743424bHLH family protein
676743482bHLH family protein
676743534bHLH family protein
676743574bHLH family protein
676744406bHLH family protein
676745718bHLH family protein
676745720bHLH family protein
676747288bHLH family protein
676747494bHLH family protein
676748370bHLH family protein
676749210bHLH family protein
676749948bHLH family protein
676750598bHLH family protein
676750732bHLH family protein
676750788bHLH family protein
676751522bHLH family protein
676751682bHLH family protein
676751756bHLH family protein
676751916bHLH family protein
676752100bHLH family protein
676752116bHLH family protein
676752298bHLH family protein
676752356bHLH family protein
676753266bHLH family protein
676753314bHLH family protein
676753470bHLH family protein
676753784bHLH family protein
676754832bHLH family protein
676755044bHLH family protein
676755262bHLH family protein
676755560bHLH family protein
676755576bHLH family protein
676755950bHLH family protein
676756222bHLH family protein
676756238bHLH family protein
676757636bHLH family protein
676758518bHLH family protein
676759562bHLH family protein
676759750bHLH family protein
676760284bHLH family protein
676760524bHLH family protein
676760886bHLH family protein
676761316bHLH family protein
676761364bHLH family protein
676762004bHLH family protein
676762530bHLH family protein
676762558bHLH family protein
676764260bHLH family protein
676765826bHLH family protein
676766070bHLH family protein
676766152bHLH family protein
676767880bHLH family protein
676768036bHLH family protein
676769160bHLH family protein
676770326bHLH family protein
676770552bHLH family protein
676774830bHLH family protein
676774836bHLH family protein
676774838bHLH family protein
676777778bHLH family protein
676777802bHLH family protein
676778830bHLH family protein
676778854bHLH family protein
676778872bHLH family protein
676778894bHLH family protein
676779766bHLH family protein
676779886bHLH family protein
676780626bHLH family protein
676780918bHLH family protein
676782186bHLH family protein
676782582bHLH family protein
676783878bHLH family protein
676784164bHLH family protein
676785214bHLH family protein
676785256bHLH family protein
676785258bHLH family protein
676785260bHLH family protein
676785262bHLH family protein
676789426bHLH family protein
676789924bHLH family protein
676789994bHLH family protein
676793050bHLH family protein
676794168bHLH family protein
676794544bHLH 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