basic Helix Loop Helix (bHLH) domain superfamily; bHLH proteins are transcriptional regulators that are found in organisms from yeast to humans. Members of the bHLH superfamily have two highly conserved and functionally distinct regions. The basic part is at the amino end of the bHLH that may bind DNA to a consensus hexanucleotide sequence known as the E box (CANNTG). Different families of bHLH proteins recognize different E-box consensus sequences. At the carboxyl-terminal end of the region is the HLH region that interacts with other proteins to form homo- and heterodimers. bHLH proteins function as a diverse set of regulatory factors because they recognize different DNA sequences and dimerize with different proteins. The bHLH proteins can be divided to cell-type specific and widely expressed proteins. The cell-type specific members of bHLH superfamily are involved in cell-fate determination and act in neurogenesis, cardiogenesis, myogenesis, and hematopoiesis.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....
gi 670373646 274 DYIHVRARRGQATDSHSLAERVRREKISERMKLLQDLVPGCSKT 317
Cdd:cd18919    1 DYIHVRARRGQATDSHSLAERVRREKISERMKLLQDLVPGCNKV 44

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana BIG PETAL (BPE) and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as BPE, HBI1 and BEE proteins (BEE1-3). BPE, also termed AtbHLH31, or EN 88, is involved in the control of Arabidopsis petal size, by interfering with postmitotic cell expansion to limit final petal cell size. HBI1, also termed AtbHLH64, or homolog of bee2 interacting with IBH1, or EN 79, is an atypical bHLH transcription factor that acts as positive regulator of cell elongation downstream of multiple external and endogenous signals by direct binding to the promoters and activation of the two expansin genes EXPA1 and EXPA8, encoding cell wall loosening enzymes. BEEs, also termed protein Brassinosteroid enhanced expression, are positive regulators of brassinosteroid signaling.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....
gi 670373646 274 DYIHVRARRGQATDSHSLAERVRREKISERMKLLQDLVPGCSKT 317
Cdd:cd18919    1 DYIHVRARRGQATDSHSLAERVRREKISERMKLLQDLVPGCNKV 44

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana BIG PETAL (BPE) and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as BPE, HBI1 and BEE proteins (BEE1-3). BPE, also termed AtbHLH31, or EN 88, is involved in the control of Arabidopsis petal size, by interfering with postmitotic cell expansion to limit final petal cell size. HBI1, also termed AtbHLH64, or homolog of bee2 interacting with IBH1, or EN 79, is an atypical bHLH transcription factor that acts as positive regulator of cell elongation downstream of multiple external and endogenous signals by direct binding to the promoters and activation of the two expansin genes EXPA1 and EXPA8, encoding cell wall loosening enzymes. BEEs, also termed protein Brassinosteroid enhanced expression, are positive regulators of brassinosteroid signaling.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....
gi 670373646 274 DYIHVRARRGQATDSHSLAERVRREKISERMKLLQDLVPGCSKT 317
Cdd:cd18919    1 DYIHVRARRGQATDSHSLAERVRREKISERMKLLQDLVPGCNKV 44

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana phytochrome interacting factors (PIFs) and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as PIFs, ALC, PIL1, SPATULA, and UNE10. PIFs (PIF1, PIF3, PIF4, PIF5, PIF6 and PIF7) have been shown to control light-regulated gene expression. They directly bind to the photoactivated phytochromes and are degraded in response to light signals. ALC, also termed AtbHLH73, or protein ALCATRAZ, or EN 98, is required for the dehiscence of fruit, especially for the separation of the valve cells from the replum. It promotes the differentiation of a strip of labile non-lignified cells sandwiched between layers of lignified cells. PIL1, also termed AtbHLH124, or protein phytochrome interacting factor 3-like 1, or EN 110, is involved in responses to transient and long-term shade. It is required for the light-mediated inhibition of hypocotyl elongation and necessary for rapid light-induced expression of the photomorphogenesis- and circadian-related gene APRR9. PIL1 seems to play a role in multiple PHYB responses, such as flowering transition and petiole elongation. SPATULA, also termed AtbHLH24, or EN 99, plays a role in floral organogenesis. It promotes the growth of carpel margins and of pollen tract tissues derived from them. UNE10, also termed AtbHLH16, or protein UNFERTILIZED EMBRYO SAC 10, or EN 99, is required during the fertilization of ovules by pollen.

                         10        20        30
                 ....*....|....*....|....*....|...
gi 670373646 285 ATDSHSLAERVRREKISERMKLLQDLVPGCSKT 317
Cdd:cd11445    2 AAEVHNLSERRRRDRINEKMKALQELIPNCNKT 34

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana BES1-interacting Myc-like proteins (BIMs) and similar proteins; The family includes Arabidopsis thaliana BIM1 and its homologs (BIM2 and BIM3), which are bHLH transcription factors that interact with BES1 to regulate transcription of Brassinosteroid (BR)-induced gene. BR regulates many growth and developmental processes such as cell elongation, vascular development, senescence stress responses, and photomorphogenesis. BIM1 heterodimerize with BES1 and bind to E-box sequences present in many BR-induced promoters to regulated BR-induced genes.

                         10        20
                 ....*....|....*....|....*.
gi 670373646 288 SHSLAERVRREKISERMKLLQDLVPG 313
Cdd:cd11453    6 KHSATEQRRRSKINERLQALRDLIPH 31

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana protein NAI1 and similar proteins; NAI1, also termed AtbHLH20, or EN 27, is a bHLH transcription activator that regulates the expression of at least NAI2, PYK10 and PBP1. It is required for and mediates the formation of endoplasmic reticulum bodies (ER bodies). It plays a role in the symbiotic interactions with the endophytes of the Sebacinaceae fungus family, such as Piriformospora indica and Sebacina.

                         10        20        30
                 ....*....|....*....|....*....|..
gi 670373646 286 TDSHSLAERVRREKISERMKLLQDLVPGCSKT 317
Cdd:cd11452    3 AQDHILAERKRREKLSQRFIALSALVPGLKKM 34

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana protein transparent testa 8 (TT8) and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as TT8, EGL1, and GL3. TT8, also termed AtbHLH42, or EN 32, is involved in the control of flavonoid pigmentation and plays a key role in regulating leucoanthocyanidin reductase (BANYULS) and dihydroflavonol-4-reductase (DFR). EGL1, also termed AtbHLH2, or EN 30, or AtMYC146, or protein enhancer of GLABRA 3, is involved in epidermal cell fate specification and regulates negatively stomata formation but promotes trichome formation. GL3, also termed AtbHLH1, or AtMYC6, or protein shapeshifter, or EN 31, is involved in epidermal cell fate specification. It regulates negatively stomata formation, but, in association with TTG1 and MYB0/GL1, promotes trichome formation, branching and endoreplication.

                         10        20        30
                 ....*....|....*....|....*....|.
gi 670373646 286 TDSHSLAERVRREKISERMKLLQDLVPGCSK 316
Cdd:cd11451    3 DGSHAMAERRRREKLNERFITLRSMVPFVTK 33

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana protein AIG1 and similar proteins; AIG1, also termed AtbHLH32, or EN 54, or protein target of MOOPTEROS 5, is a transcription factor required for MONOPTEROS-dependent root initiation in embryo.

                         10        20        30
                 ....*....|....*....|....*....|....*...
gi 670373646 280 ARRGQATDSHSLAERVRREKISERMKLLQDLVPGCSKT 317
Cdd:cd11455    2 DKALAASKSHSEAERRRRERINSHLATLRTLLPNLSKT 39