PlantTFDB
Plant Transcription Factor Database
v4.0
Previous version: v1.0, v2.0, v3.0
Vigna unguiculata
bHLH Family
Species TF ID Description
Vun000261bHLH family protein
Vun000331bHLH family protein
Vun000915bHLH family protein
Vun000916bHLH family protein
Vun000943bHLH family protein
Vun001364bHLH family protein
Vun001452bHLH family protein
Vun001732bHLH family protein
Vun001902bHLH family protein
Vun001938bHLH family protein
Vun001982bHLH family protein
Vun002081bHLH family protein
Vun002089bHLH family protein
Vun002228bHLH family protein
Vun002352bHLH family protein
Vun002661bHLH family protein
Vun002793bHLH family protein
Vun003098bHLH family protein
Vun003157bHLH family protein
Vun003348bHLH family protein
Vun003643bHLH family protein
Vun003692bHLH family protein
Vun003813bHLH family protein
Vun003951bHLH family protein
Vun004104bHLH family protein
Vun004133bHLH family protein
Vun004240bHLH family protein
Vun004395bHLH family protein
Vun004419bHLH family protein
Vun004469bHLH family protein
Vun004906bHLH family protein
Vun005022bHLH family protein
Vun005265bHLH family protein
Vun005416bHLH family protein
Vun005710bHLH family protein
Vun005732bHLH family protein
Vun005858bHLH family protein
Vun005901bHLH family protein
Vun006304bHLH family protein
Vun007075bHLH family protein
Vun007315bHLH family protein
Vun008133bHLH family protein
Vun008510bHLH family protein
Vun008537bHLH family protein
Vun008703bHLH family protein
Vun009040bHLH family protein
Vun009060bHLH family protein
Vun009105bHLH family protein
Vun009135bHLH family protein
Vun009145bHLH family protein
Vun009198bHLH family protein
Vun009252bHLH family protein
Vun009332bHLH family protein
Vun009345bHLH family protein
Vun009681bHLH family protein
Vun010029bHLH family protein
Vun010260bHLH family protein
Vun010426bHLH family protein
Vun010817bHLH family protein
Vun011038bHLH family protein
Vun011656bHLH 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