PlantTFDB
Plant Transcription Factor Database
v4.0
Previous version: v1.0, v2.0, v3.0
Arabidopsis lyrata
bHLH Family
Species TF ID Description
312099bHLH family protein
312791bHLH family protein
313705bHLH family protein
319546bHLH family protein
324207bHLH family protein
327641bHLH family protein
327725bHLH family protein
329503bHLH family protein
332092bHLH family protein
333565bHLH family protein
333922bHLH family protein
335492bHLH family protein
337131bHLH family protein
342085bHLH family protein
347878bHLH family protein
348075bHLH family protein
353119bHLH family protein
354244bHLH family protein
354651bHLH family protein
358332bHLH family protein
358733bHLH family protein
470147bHLH family protein
470281bHLH family protein
470588bHLH family protein
471048bHLH family protein
471177bHLH family protein
471184bHLH family protein
471403bHLH family protein
472704bHLH family protein
472791bHLH family protein
472840bHLH family protein
472970bHLH family protein
472979bHLH family protein
473207bHLH family protein
474224bHLH family protein
474229bHLH family protein
474990bHLH family protein
475056bHLH family protein
475161bHLH family protein
475944bHLH family protein
476008bHLH family protein
476021bHLH family protein
476029bHLH family protein
476520bHLH family protein
476585bHLH family protein
477966bHLH family protein
479503bHLH family protein
479653bHLH family protein
479835bHLH family protein
480366bHLH family protein
480571bHLH family protein
480739bHLH family protein
481136bHLH family protein
481137bHLH family protein
481138bHLH family protein
481281bHLH family protein
481693bHLH family protein
482048bHLH family protein
482049bHLH family protein
482096bHLH family protein
483066bHLH family protein
483321bHLH family protein
483401bHLH family protein
483415bHLH family protein
483808bHLH family protein
484332bHLH family protein
484449bHLH family protein
485129bHLH family protein
485384bHLH family protein
486116bHLH family protein
486140bHLH family protein
486233bHLH family protein
486700bHLH family protein
486946bHLH family protein
487795bHLH family protein
487890bHLH family protein
489790bHLH family protein
489834bHLH family protein
490301bHLH family protein
490556bHLH family protein
491027bHLH family protein
491205bHLH family protein
491291bHLH family protein
491651bHLH family protein
491763bHLH family protein
492289bHLH family protein
492747bHLH family protein
493087bHLH family protein
493462bHLH family protein
493759bHLH family protein
493847bHLH family protein
494310bHLH family protein
494687bHLH family protein
494918bHLH family protein
495154bHLH family protein
495243bHLH family protein
495549bHLH family protein
495811bHLH family protein
496441bHLH family protein
496718bHLH family protein
496795bHLH family protein
496889bHLH family protein
496895bHLH family protein
497265bHLH family protein
497417bHLH family protein
855794bHLH family protein
856734bHLH family protein
856896bHLH family protein
860820bHLH family protein
864079bHLH family protein
864421bHLH family protein
869370bHLH family protein
869422bHLH family protein
869802bHLH family protein
870571bHLH family protein
872116bHLH family protein
873720bHLH family protein
873923bHLH family protein
877212bHLH family protein
879201bHLH family protein
879559bHLH family protein
881438bHLH family protein
882577bHLH family protein
883868bHLH family protein
885286bHLH family protein
885448bHLH family protein
885879bHLH family protein
887762bHLH family protein
888270bHLH family protein
890840bHLH family protein
891198bHLH family protein
892725bHLH family protein
893615bHLH family protein
894298bHLH family protein
896721bHLH family protein
898955bHLH family protein
902147bHLH family protein
903419bHLH family protein
903576bHLH family protein
904152bHLH family protein
904169bHLH family protein
905167bHLH family protein
907404bHLH family protein
907776bHLH family protein
907786bHLH family protein
908762bHLH family protein
909486bHLH family protein
912247bHLH family protein
913602bHLH family protein
913634bHLH family protein
915109bHLH family protein
916307bHLH family protein
916432bHLH family protein
916752bHLH family protein
920517bHLH 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