helix loop helix domain;

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|
gi 1063680621   38 ERK--DKVGERISALQQIVsPYG----KTDTASVLLDAMHYIEFLHEQVK 81
Cdd:smart00353   4 ERRrrRKINEAFDELRSLL-PTLpknkKLSKAEILRLAIEYIKSLQEELQ 52

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana protein INDEHISCENT (IND) and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as IND, HEC proteins (HEC1, HEC2 and HEC3) and UNE12. IND, also termed AtbHLH40, or EN 120, is a bHLH transcription regulator required for seed dispersal. It is involved in the differentiation of all three cell types required for fruit dehiscence. HEC1 (also termed AtbHLH88, or protein HECATE 1, or EN 118), HEC2 (also termed AtbHLH37, or protein HECATE 2, or EN 117) and HEC3 (also termed AtbHLH43, or protein HECATE 3, or EN 119) are required for the female reproductive tract development and fertility. Both IND and HEC proteins have been implicated in regulation of auxin signaling. They heterodimerize with SPATULA (SPT) bHLH transcription factor to regulate reproductive tract development in plant. UNE12, also termed AtbHLH59, or protein UNFERTILIZED EMBRYO SAC 12, or EN 93, is required for ovule fertilization.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1063680621  33 SFSSKERKDKVGERISALQQIVSPYGKTDTASVLLDAMHYIEFLHEQVKVCSS 85
Cdd:cd11454     6 SVAARHRRERISERIRILQRLVPGGTKMDTASMLDEAIHYVKFLQLQVKLLQS 58

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        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*.
gi 1063680621  35 SSKERKDKVGERISALQQIVSPYGKTDTASVLLDAMHYIEFLHEQVKVCSSIPSMI 90
Cdd:cd11445     9 SERRRRDRINEKMKALQELIPNCNKTDKASMLDEAIEYLKSLQLQVQMMSMGNGMP 64

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana protein ABA-INDUCIBLE bHLH-TYPE (AIB) and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as AIB and MYC proteins (MYC2, MYC3 and MYC4). AIB, also termed AtbHLH17, or EN 35, is a transcription activator that regulates positively abscisic acid (ABA) response. MYC2, also termed protein jasmonate insensitive 1, or R-homologous Arabidopsis protein 1 (RAP-1), or AtbHLH6, or EN 38, or Z-box binding factor 1 protein, is a transcriptional activator involved in abscisic acid (ABA), jasmonic acid (JA), and light signaling pathways. MYC3, also termed protein altered tryptophan regulation 2, or AtbHLH5, or transcription factor ATR2, or EN 36, is a transcription factor involved in tryptophan, jasmonic acid (JA) and other stress-responsive gene regulation. MYC4, also termed AtbHLH4, or EN 37, is a transcription factor involved in jasmonic acid (JA) gene regulation. MYC2, together with MYC3 and MYC4, controls additively subsets of JA-dependent responses.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 1063680621  37 KERKDKVGERISALQQIVSPYGKTDTASVLLDAMHYIEFLHEQVKV 82
Cdd:cd11449    14 RQRREKLNQRFYALRAVVPNVSKMDKASLLGDAISYINELKSKVQD 59

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana Fe-deficiency induced transcription factor 1 (FIT) and similar proteins; The family includes bHLH transcription factors from Arabidopsis thaliana, such as FIT and DYT1. FIT, also termed FER-like iron deficiency-induced transcription factor, or FER-like regulator of iron uptake, or AtbHLH29, or EN 43, is a bHLH transcription factor that is required for the iron deficiency response in plant. It regulates FRO2 at the level of mRNA accumulation and IRT1 at the level of protein accumulation. DYT1, also termed AtbHLH22, or protein dysfunctional tapetum 1, or EN 49, is a bHLH transcription factor involved in the control of tapetum development. It is required for male fertility and pollen differentiation, especially during callose deposition.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*..
gi 1063680621  35 SSKERKDKVGERISALQQIVSPYGKTDTASVLLDAMHYIEFLHEQVK 81
Cdd:cd11450    10 SERNRRQKLNQRLFALRSVVPNITKMDKASIIKDAISYIQELQYQEK 56

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana ILI1-BINDING BHLH 1 (IBH1) and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as IBH1, UPBEAT1, PAR1 and PAR2. IBH1, also termed bHLH zeta, or AtbHLH158, is an atypical and probable non DNA-binding bHLH transcription factor that acts as transcriptional repressor that negatively regulates cell and organ elongation in response to gibberellin (GA) and brassinosteroid (BR) signaling. IBH1 forms heterodimer with BHLH49, thus inhibiting DNA binding of BHLH49, which is a transcriptional activator that regulates the expression of a subset of genes involved in cell expansion by binding to the G-box motif. UPBEAT1, also termed AtbHLH151, or EN 146, is a bHLH transcription factor that modulates the balance between cellular proliferation and differentiation in root growth. It does not act through cytokinin and auxin signaling, but by repressing peroxidase expression in the elongation zone. PAR1 (also termed AtbHLH165, or protein helix-loop-helix 1, or protein phytochrome rapidly regulated 1) and PAR2 (also termed AtbHLH166, or protein helix-loop-helix 2, or protein phytochrome rapidly regulated 2) are two atypical bHLH transcription factors that act as negative regulators of a variety of shade avoidance syndrome (SAS) responses, including seedling elongation and photosynthetic pigment accumulation. They act as direct transcriptional repressor of two auxin-responsive genes, SAUR15 and SAUR68. They may function in integrating shade and hormone transcriptional networks in response to light and auxin changes.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1063680621  35 SSKERKDKVGERISALQQIVsPYGKTDTA-SVLLD-AMHYIEFLHEQVKVCSSI 86
Cdd:cd11444     4 RRRRGEEAIERRLRALRRLV-PGGRESMEvEELLQeTADYIMFLEMQVKVMKSL 56