PlantTFDB
Plant Transcription Factor Database
v4.0
Previous version: v1.0, v2.0, v3.0
Oropetium thomaeum
bHLH Family
Species TF ID Description
Oropetium_20150105_00222AbHLH family protein
Oropetium_20150105_00226AbHLH family protein
Oropetium_20150105_00325AbHLH family protein
Oropetium_20150105_00600AbHLH family protein
Oropetium_20150105_00761AbHLH family protein
Oropetium_20150105_00910AbHLH family protein
Oropetium_20150105_01533AbHLH family protein
Oropetium_20150105_01578AbHLH family protein
Oropetium_20150105_01711AbHLH family protein
Oropetium_20150105_01786AbHLH family protein
Oropetium_20150105_02254AbHLH family protein
Oropetium_20150105_02498AbHLH family protein
Oropetium_20150105_02689AbHLH family protein
Oropetium_20150105_03010AbHLH family protein
Oropetium_20150105_03041AbHLH family protein
Oropetium_20150105_03191AbHLH family protein
Oropetium_20150105_03703AbHLH family protein
Oropetium_20150105_03723AbHLH family protein
Oropetium_20150105_04095AbHLH family protein
Oropetium_20150105_04204AbHLH family protein
Oropetium_20150105_04275AbHLH family protein
Oropetium_20150105_04499AbHLH family protein
Oropetium_20150105_04560AbHLH family protein
Oropetium_20150105_04766AbHLH family protein
Oropetium_20150105_04912AbHLH family protein
Oropetium_20150105_05516AbHLH family protein
Oropetium_20150105_05601AbHLH family protein
Oropetium_20150105_05625AbHLH family protein
Oropetium_20150105_05690AbHLH family protein
Oropetium_20150105_06042AbHLH family protein
Oropetium_20150105_06082AbHLH family protein
Oropetium_20150105_06656AbHLH family protein
Oropetium_20150105_06713AbHLH family protein
Oropetium_20150105_06864AbHLH family protein
Oropetium_20150105_06889AbHLH family protein
Oropetium_20150105_06890AbHLH family protein
Oropetium_20150105_06891AbHLH family protein
Oropetium_20150105_06913AbHLH family protein
Oropetium_20150105_07180AbHLH family protein
Oropetium_20150105_07413AbHLH family protein
Oropetium_20150105_07509AbHLH family protein
Oropetium_20150105_07663AbHLH family protein
Oropetium_20150105_07774AbHLH family protein
Oropetium_20150105_07869AbHLH family protein
Oropetium_20150105_08228AbHLH family protein
Oropetium_20150105_08394AbHLH family protein
Oropetium_20150105_08823AbHLH family protein
Oropetium_20150105_08883AbHLH family protein
Oropetium_20150105_08972AbHLH family protein
Oropetium_20150105_09059AbHLH family protein
Oropetium_20150105_09845AbHLH family protein
Oropetium_20150105_09967AbHLH family protein
Oropetium_20150105_10203AbHLH family protein
Oropetium_20150105_10476AbHLH family protein
Oropetium_20150105_10899AbHLH family protein
Oropetium_20150105_11155AbHLH family protein
Oropetium_20150105_11403AbHLH family protein
Oropetium_20150105_11404AbHLH family protein
Oropetium_20150105_12337AbHLH family protein
Oropetium_20150105_12679AbHLH family protein
Oropetium_20150105_12753AbHLH family protein
Oropetium_20150105_13099AbHLH family protein
Oropetium_20150105_13550AbHLH family protein
Oropetium_20150105_13582AbHLH family protein
Oropetium_20150105_13681AbHLH family protein
Oropetium_20150105_14157AbHLH family protein
Oropetium_20150105_14187AbHLH family protein
Oropetium_20150105_14598AbHLH family protein
Oropetium_20150105_14650AbHLH family protein
Oropetium_20150105_15478AbHLH family protein
Oropetium_20150105_15887AbHLH family protein
Oropetium_20150105_16416AbHLH family protein
Oropetium_20150105_16702AbHLH family protein
Oropetium_20150105_17058AbHLH family protein
Oropetium_20150105_17116AbHLH family protein
Oropetium_20150105_17252AbHLH family protein
Oropetium_20150105_17309AbHLH family protein
Oropetium_20150105_17444AbHLH family protein
Oropetium_20150105_17766AbHLH family protein
Oropetium_20150105_17891AbHLH family protein
Oropetium_20150105_18128AbHLH family protein
Oropetium_20150105_18173AbHLH family protein
Oropetium_20150105_18212AbHLH family protein
Oropetium_20150105_18775AbHLH family protein
Oropetium_20150105_18927AbHLH family protein
Oropetium_20150105_19069AbHLH family protein
Oropetium_20150105_19168AbHLH family protein
Oropetium_20150105_19271AbHLH family protein
Oropetium_20150105_19306AbHLH family protein
Oropetium_20150105_19340AbHLH family protein
Oropetium_20150105_19386AbHLH family protein
Oropetium_20150105_19590AbHLH family protein
Oropetium_20150105_19695AbHLH family protein
Oropetium_20150105_19790AbHLH family protein
Oropetium_20150105_20004AbHLH family protein
Oropetium_20150105_20136AbHLH family protein
Oropetium_20150105_20246AbHLH family protein
Oropetium_20150105_20331AbHLH family protein
Oropetium_20150105_20373AbHLH family protein
Oropetium_20150105_20385AbHLH family protein
Oropetium_20150105_20418AbHLH family protein
Oropetium_20150105_20688AbHLH family protein
Oropetium_20150105_20973AbHLH family protein
Oropetium_20150105_21450AbHLH family protein
Oropetium_20150105_21564AbHLH family protein
Oropetium_20150105_22523AbHLH family protein
Oropetium_20150105_22554AbHLH family protein
Oropetium_20150105_22628AbHLH family protein
Oropetium_20150105_22669AbHLH family protein
Oropetium_20150105_22939AbHLH family protein
Oropetium_20150105_22956AbHLH family protein
Oropetium_20150105_22978AbHLH family protein
Oropetium_20150105_23025AbHLH family protein
Oropetium_20150105_23256AbHLH family protein
Oropetium_20150105_23269AbHLH family protein
Oropetium_20150105_23327AbHLH family protein
Oropetium_20150105_23465AbHLH family protein
Oropetium_20150105_23951AbHLH family protein
Oropetium_20150105_24050AbHLH family protein
Oropetium_20150105_25384AbHLH family protein
Oropetium_20150105_25743AbHLH family protein
Oropetium_20150105_26110AbHLH family protein
Oropetium_20150105_26357AbHLH family protein
Oropetium_20150105_26524AbHLH family protein
Oropetium_20150105_27225AbHLH family protein
Oropetium_20150105_27450AbHLH family protein
Oropetium_20150105_27568AbHLH family protein
Oropetium_20150105_27750AbHLH family protein
Oropetium_20150105_28215AbHLH family protein
Oropetium_20150105_28232AbHLH 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