PlantTFDB
Plant Transcription Factor Database
v4.0
Previous version: v1.0, v2.0, v3.0
Ananas comosus
bHLH Family
Species TF ID Description
Aco000179.1bHLH family protein
Aco000186.1bHLH family protein
Aco000272.1bHLH family protein
Aco000605.1bHLH family protein
Aco000773.1bHLH family protein
Aco000904.1bHLH family protein
Aco000913.1bHLH family protein
Aco001074.1bHLH family protein
Aco001133.1bHLH family protein
Aco001136.1bHLH family protein
Aco001255.1bHLH family protein
Aco001282.1bHLH family protein
Aco001331.1bHLH family protein
Aco002151.1bHLH family protein
Aco002225.1bHLH family protein
Aco002246.1bHLH family protein
Aco002333.1bHLH family protein
Aco002862.1bHLH family protein
Aco003064.1bHLH family protein
Aco003149.1bHLH family protein
Aco003204.1bHLH family protein
Aco003613.1bHLH family protein
Aco004054.1bHLH family protein
Aco004136.1bHLH family protein
Aco004138.1bHLH family protein
Aco004377.1bHLH family protein
Aco004559.1bHLH family protein
Aco004647.1bHLH family protein
Aco004686.1bHLH family protein
Aco004914.1bHLH family protein
Aco005342.1bHLH family protein
Aco005770.1bHLH family protein
Aco005839.1bHLH family protein
Aco005872.1bHLH family protein
Aco006737.1bHLH family protein
Aco007275.1bHLH family protein
Aco008079.1bHLH family protein
Aco008553.1bHLH family protein
Aco008686.1bHLH family protein
Aco009100.1bHLH family protein
Aco009603.1bHLH family protein
Aco009661.1bHLH family protein
Aco009909.1bHLH family protein
Aco010168.1bHLH family protein
Aco010345.1bHLH family protein
Aco010678.1bHLH family protein
Aco010845.1bHLH family protein
Aco010917.1bHLH family protein
Aco011121.1bHLH family protein
Aco011419.1bHLH family protein
Aco011852.1bHLH family protein
Aco011855.1bHLH family protein
Aco011934.1bHLH family protein
Aco011985.1bHLH family protein
Aco012028.1bHLH family protein
Aco012193.1bHLH family protein
Aco012350.1bHLH family protein
Aco012482.1bHLH family protein
Aco012714.1bHLH family protein
Aco012816.1bHLH family protein
Aco012937.1bHLH family protein
Aco013073.1bHLH family protein
Aco013092.1bHLH family protein
Aco013347.1bHLH family protein
Aco013365.1bHLH family protein
Aco013643.1bHLH family protein
Aco014156.1bHLH family protein
Aco014442.1bHLH family protein
Aco014447.1bHLH family protein
Aco014454.1bHLH family protein
Aco014880.1bHLH family protein
Aco014894.1bHLH family protein
Aco015075.1bHLH family protein
Aco015158.1bHLH family protein
Aco015791.1bHLH family protein
Aco015882.1bHLH family protein
Aco016081.1bHLH family protein
Aco016125.1bHLH family protein
Aco016398.1bHLH family protein
Aco016415.1bHLH family protein
Aco016434.1bHLH family protein
Aco016776.1bHLH family protein
Aco016928.1bHLH family protein
Aco017264.1bHLH family protein
Aco017355.1bHLH family protein
Aco017396.1bHLH family protein
Aco018208.1bHLH family protein
Aco018875.1bHLH family protein
Aco018903.1bHLH family protein
Aco019347.1bHLH family protein
Aco019856.1bHLH family protein
Aco020380.1bHLH family protein
Aco020381.1bHLH family protein
Aco020569.1bHLH family protein
Aco021068.1bHLH family protein
Aco021761.1bHLH family protein
Aco021969.1bHLH family protein
Aco021976.1bHLH family protein
Aco021988.1bHLH family protein
Aco022096.1bHLH family protein
Aco022880.1bHLH family protein
Aco023468.1bHLH family protein
Aco023503.1bHLH family protein
Aco023519.1bHLH family protein
Aco024469.1bHLH family protein
Aco025287.1bHLH family protein
Aco025362.1bHLH family protein
Aco025839.1bHLH family protein
Aco026239.1bHLH family protein
Aco026511.1bHLH family protein
Aco026878.1bHLH family protein
Aco027360.1bHLH family protein
Aco027896.1bHLH family protein
Aco027966.1bHLH family protein
Aco027975.1bHLH family protein
Aco028213.1bHLH family protein
Aco028872.1bHLH family protein
Aco029228.1bHLH family protein
Aco030561.1bHLH family protein
Aco030901.1bHLH family protein
Aco031432.1bHLH 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