ACT domains are commonly involved in specifically binding an amino acid or other small ligand leading to regulation of the enzyme; Members of this CD belong to the superfamily of ACT regulatory domains. Pairs of ACT domains are commonly involved in specifically binding an amino acid or other small ligand leading to regulation of the enzyme. The ACT domain has been detected in a number of diverse proteins; some of these proteins are involved in amino acid and purine biosynthesis, phenylalanine hydroxylation, regulation of bacterial metabolism and transcription, and many remain to be characterized. ACT domain-containing enzymes involved in amino acid and purine synthesis are in many cases allosteric enzymes with complex regulation enforced by the binding of ligands. The ACT domain is commonly involved in the binding of a small regulatory molecule, such as the amino acids L-Ser and L-Phe in the case of D-3-phosphoglycerate dehydrogenase and the bifunctional chorismate mutase-prephenate dehydratase enzyme (P-protein), respectively. Aspartokinases typically consist of two C-terminal ACT domains in a tandem repeat, but the second ACT domain is inserted within the first, resulting in, what is normally the terminal beta strand of ACT2, formed from a region N-terminal of ACT1. ACT domain repeats have been shown to have nonequivalent ligand-binding sites with complex regulatory patterns such as those seen in the bifunctional enzyme, aspartokinase-homoserine dehydrogenase (ThrA). In other enzymes, such as phenylalanine hydroxylases, the ACT domain appears to function as a flexible small module providing allosteric regulation via transmission of conformational changes, these conformational changes are not necessarily initiated by regulatory ligand binding at the ACT domain itself. ACT domains are present either singularly, N- or C-terminal, or in pairs present C-terminal or between two catalytic domains. Unique to cyanobacteria are four ACT domains C-terminal to an aspartokinase domain. A few proteins are composed almost entirely of ACT domain repeats as seen in the four ACT domain protein, the ACR protein, found in higher plants; and the two ACT domain protein, the glycine cleavage system transcriptional repressor (GcvR) protein, found in some bacteria. Also seen are single ACT domain proteins similar to the Streptococcus pneumoniae ACT domain protein (uncharacterized pdb structure 1ZPV) found in both bacteria and archaea. Purportedly, the ACT domain is an evolutionarily mobile ligand binding regulatory module that has been fused to different enzymes at various times.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 470122226 245 SLCCEDRSDLLPDLIKTLKALRLRTLKAEITTLGGRVKNVLFITGEEDHSSSGEEQQQycissIQEALKAVM 316
Cdd:cd04899    4 ELTALDRPGLLADVTRVLAELGLNIHSAKIATLGERAEDVFYVTDADGQPLDPERQEA-----LRAALGEAL 70

C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD and related domains; This ACT domain family, ACT_ACR-UUR-like_2, includes the second of two C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; including those enzymes similar to the GlnD found in enteric Escherichia coli and those found in photosynthetic, nitrogen-fixing bacterium Rhodospirillum rubrum. Also included in this CD are the second and fourth ACT domains of a novel protein composed almost entirely of ACT domain repeats, the ACR protein. These ACR proteins, found in Arabidopsis and Oryza, are proposed to function as novel regulatory or sensor proteins in plants. Members of this CD belong to the superfamily of ACT regulatory domains.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 470122226 245 SLCCEDRSDLLPDLIKTLKALRLRTLKAEITTLGGRVKNVLFITGEEDHSSSGEEQQQycissIQEALKAVM 316
Cdd:cd04899    4 ELTALDRPGLLADVTRVLAELGLNIHSAKIATLGERAEDVFYVTDADGQPLDPERQEA-----LRAALGEAL 70

helix loop helix domain;

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|...
gi 470122226   172 RERINNHLAKLRSLLP---STTKTDKASLLAEVIQHVKELKRQ 211
Cdd:smart00353   8 RRKINEAFDELRSLLPtlpKNKKLSKAEILRLAIEYIKSLQEE 50

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana genes coding transcription factors and similar proteins; bHLH proteins are the second largest class of plant transcription factors that regulate transcription of genes that are involve in many essential physiological and developmental process. bHLH proteins are transcriptional regulators that are found in organisms from yeast to humans. The Arabidopsis bHLH proteins that have been characterized so far have roles in regulation of fruit dehiscence, cell development (carpel, anther and epidermal), phytochrome signaling, flavonoid biosynthesis, hormone signaling and stress responses.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 470122226 164 HSEAERRRRERINNHLAKLRSLLPSTTKTDKASLLAEVIQHVKELKRQTSV 214
Cdd:cd11393    1 HSIAERKRREKINERIRALRSLVPNGGKTDKASILDEAIEYIKFLQEQVKV 51

ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; This ACT domain family, ACT_UUR_ACR-like, includes the two C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; including those enzymes similar to the GlnD found in enteric Escherichia coli and those found in photosynthetic, nitrogen-fixing bacterium Rhodospirillum rubrum. Also included in this CD are the four ACT domains of a novel protein composed almost entirely of ACT domain repeats (the ACR protein) and like proteins. These ACR proteins, found in Arabidopsis and Oryza, are proposed to function as novel regulatory or sensor proteins in plants. This CD also includes the first of the two ACT domains that comprise the Glycine Cleavage System Transcriptional Repressor (GcvR) protein and related domains, as well as, the N-terminal ACT domain of a yet characterized Arabidopsis/Oryza predicted tyrosine kinase. Members of this CD belong to the superfamily of ACT regulatory domains.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 470122226 245 SLCCEDRSDLLPDLIKTLKALRLRTLKAEITTLGGRVKNVLFITGEEDHSSSGEEQQqycisSIQEALKAVM 316
Cdd:cd04873    4 EVYAPDRPGLLADITRVLADLGLNIHDARISTTGERALDVFYVTDSDGRPLDPERIA-----RLEEALEDAL 70

basic Helix-Loop-Helix (bHLH) domain found in Arabidopsis thaliana MYC1 and similar proteins; MYC1, also termed AtbHLH12, or EN 58, acts as a transcription activator, when associated with MYB75/PAP1 or MYB90/PAP2.

                         10        20        30
                 ....*....|....*....|....*....|....*...
gi 470122226 174 RINNHLAKLRSLLPSTTKTDKASLLAEVIQHVKELKRQ 211
Cdd:cd18918   11 KLNEKFSDLRNLIPNPTKNDRASILSDAIKYINELQRT 48

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        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 470122226 163 SHSEAERRRRERINNHLAKLRSLLPSTTKTDKASLLAEVIQHVKELKRQ------TSVIAETSPVPT 223
Cdd:cd11451    5 SHAMAERRRREKLNERFITLRSMVPFVTKMDKVSILGDAIEYLKQLQRRveelesRRKSSDTETRPT 71

helix loop helix domain;

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|...
gi 470122226   172 RERINNHLAKLRSLLP---STTKTDKASLLAEVIQHVKELKRQ 211
Cdd:smart00353   8 RRKINEAFDELRSLLPtlpKNKKLSKAEILRLAIEYIKSLQEE 50

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        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 470122226 153 MDAKALAASKSHseaerrrrERINNHLAKLRSLLPSTTKTDKASLLAEVIQHVKELKRQTSVIAETSPVP 222
Cdd:cd11454    2 TDPQSVAARHRR--------ERISERIRILQRLVPGGTKMDTASMLDEAIHYVKFLQLQVKLLQSDDLWM 63

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        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 470122226 172 RERINNHLAKLRSLLPSTTKTDKASLLAEVIQHVKEL----KRQTSVIAETSPVPTETDELV 229
Cdd:cd11450   15 RQKLNQRLFALRSVVPNITKMDKASIIKDAISYIQELqyqeKKLEAEIRELESRPPSTLSFQ 76

Helix-loop-helix DNA-binding domain;

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|.
gi 470122226  172 RERINNHLAKLRSLLPST---TKTDKASLLAEVIQHVKELK 209
Cdd:pfam00010  13 RDRINDAFDELRELLPTLppdKKLSKAEILRLAIEYIKHLQ 53

basic helix-loop-helix (bHLH) domain found in Arabidopsis thaliana protein FAMA and similar proteins; The family includes several bHLH transcription factors from Arabidopsis thaliana, such as FAMA, MUTE and SPEECHLESS, which work together to regulate the sequential cell fate specification during stomatal development and differentiation. FAMA, also termed AtbHLH97, or EN 14, is a transcription activator required to promote differentiation and morphogenesis of stomatal guard cells and to halt proliferative divisions in their immediate precursors. It mediates the formation of stomata. MUTE, also termed AtbHLH45, or EN 20, is required for the differentiation of stomatal guard cells, by promoting successive asymmetric cell divisions and the formation of guard mother cells. It promotes the conversion of the leaf epidermis into stomata. SPEECHLESS, also termed AtbHLH98, or EN 19, is required for the initiation and the formation of stomata, by promoting the first asymmetric cell divisions. FAMA, MUTE and SPEECHLESS form heterodimers with SCREAM/ICE1 and SCRM2 to regulate transcription of genes during stomatal development.

                         10        20        30
                 ....*....|....*....|....*....|....*
gi 470122226 176 NNHLAKLRSLLPST--TKTDKASLLAEVIQHVKEL 208
Cdd:cd11448   15 NEHLNVLRSLMPGSyiQRGDQASIVGGAIEFVKEL 49

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        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 470122226 161 SKSHSEAERRRRERINNHLAKLRSLLPSTTKTDKASLLAEVIQHVKELKRQTSVIAETSPVPTETDELVV 230
Cdd:cd11452    3 AQDHILAERKRREKLSQRFIALSALVPGLKKMDKASVLGDAIKHIKQLQERVKELEEEKKEKRLMSVVIV 72

Second ACT domain, of a novel type of ACT domain-containing protein which is composed almost entirely of four ACT domain repeats (the "ACR" protein); This CD includes the second ACT domain, of a novel type of ACT domain-containing protein which is composed almost entirely of four ACT domain repeats (the "ACR" protein). ACR proteins, found only in Arabidopsis and Oryza, as yet, are proposed to function as novel regulatory or sensor proteins in plants. Nine ACR gene products (ACR1-8 in Arabidopsis and OsARC1-9 in Oryza) have been described, however, the ACR-like sequences in this CD are distinct from those characterized. This CD includes the Oryza sativa ACR-like protein (Os05g0113000) encoded on chromosome 5 and the Arabidopsis thaliana predicted gene product, At2g39570. Members of this CD belong to the superfamily of ACT regulatory domains.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 470122226 240 FVIKasLCCEDRSDLLPDLIKTLKALRLRTLKAEI-TTLGGRVKNVLFITGEEDHSSSGEEQQQYCissiqEALKAVMEK 318
Cdd:cd04927    1 FLLK--LFCSDRKGLLHDVTEVLYELELTIERVKVsTTPDGRVLDLFFITDARELLHTKKRREETY-----DYLRAVLGD 73

                 ..
gi 470122226 319 SG 320
Cdd:cd04927   74 SM 75