PlantTFDB
Plant Transcription Factor Database
v4.0
Previous version: v1.0, v2.0, v3.0
Ricinus communis
bHLH Family
Species TF ID Description
27469.m000162bHLH family protein
27733.m000033bHLH family protein
27749.m000334bHLH family protein
27751.m000168bHLH family protein
27751.m000169bHLH family protein
27964.m000352bHLH family protein
27964.m000356bHLH family protein
27996.m000153bHLH family protein
28152.m000885bHLH family protein
28152.m000914bHLH family protein
28166.m001054bHLH family protein
28179.m000457bHLH family protein
28179.m000478bHLH family protein
28179.m000479bHLH family protein
28405.m000015bHLH family protein
28567.m000052bHLH family protein
28609.m000209bHLH family protein
29216.m000261bHLH family protein
29222.m000411bHLH family protein
29222.m000412bHLH family protein
29447.m000032bHLH family protein
29585.m000603bHLH family protein
29589.m001259bHLH family protein
29596.m000688bHLH family protein
29598.m000464bHLH family protein
29603.m000513bHLH family protein
29631.m001025bHLH family protein
29631.m001038bHLH family protein
29631.m001039bHLH family protein
29634.m002080bHLH family protein
29646.m001078bHLH family protein
29647.m002101bHLH family protein
29647.m002113bHLH family protein
29660.m000750bHLH family protein
29693.m002046bHLH family protein
29711.m000322bHLH family protein
29736.m002007bHLH family protein
29736.m002076bHLH family protein
29737.m001209bHLH family protein
29738.m001043bHLH family protein
29739.m003684bHLH family protein
29742.m001404bHLH family protein
29780.m001358bHLH family protein
29790.m000843bHLH family protein
29801.m003163bHLH family protein
29804.m001498bHLH family protein
29814.m000735bHLH family protein
29822.m003497bHLH family protein
29827.m002528bHLH family protein
29830.m001386bHLH family protein
29842.m003681bHLH family protein
29842.m003700bHLH family protein
29842.m003704bHLH family protein
29844.m003167bHLH family protein
29844.m003312bHLH family protein
29869.m001184bHLH family protein
29869.m001185bHLH family protein
29869.m001188bHLH family protein
29869.m001189bHLH family protein
29883.m001988bHLH family protein
29883.m002023bHLH family protein
29900.m001610bHLH family protein
29904.m002956bHLH family protein
29908.m006098bHLH family protein
29908.m006255bHLH family protein
29912.m005337bHLH family protein
29912.m005485bHLH family protein
29970.m001001bHLH family protein
29974.m000242bHLH family protein
29983.m003179bHLH family protein
30054.m000819bHLH family protein
30066.m000713bHLH family protein
30066.m000750bHLH family protein
30066.m000752bHLH family protein
30068.m002581bHLH family protein
30074.m001421bHLH family protein
30076.m004456bHLH family protein
30076.m004542bHLH family protein
30115.m001220bHLH family protein
30115.m001235bHLH family protein
30128.m008737bHLH family protein
30128.m008923bHLH family protein
30128.m008988bHLH family protein
30128.m009052bHLH family protein
30131.m006993bHLH family protein
30131.m007045bHLH family protein
30136.m001043bHLH family protein
30138.m003881bHLH family protein
30138.m003899bHLH family protein
30138.m003913bHLH family protein
30138.m004021bHLH family protein
30146.m003443bHLH family protein
30147.m013968bHLH family protein
30147.m014038bHLH family protein
30147.m014102bHLH family protein
30147.m014106bHLH family protein
30147.m014112bHLH family protein
30147.m014145bHLH family protein
30147.m014146bHLH family protein
30147.m014147bHLH family protein
30147.m014419bHLH family protein
30147.m014428bHLH family protein
30149.m000231bHLH family protein
30152.m002405bHLH family protein
30156.m001712bHLH family protein
30169.m006403bHLH family protein
30169.m006534bHLH family protein
30170.m013667bHLH family protein
30170.m013700bHLH family protein
30170.m013749bHLH family protein
30170.m013852bHLH family protein
30170.m013861bHLH family protein
30170.m014085bHLH family protein
30174.m008814bHLH family protein
30180.m001071bHLH family protein
30183.m001293bHLH family protein
30190.m010874bHLH family protein
30190.m011223bHLH family protein
30198.m000869bHLH family protein
30204.m001816bHLH family protein
50006.m000011bHLH 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