The ligand binding domain of nuclear receptors, a family of ligand-activated transcription regulators; Ligand-binding domain (LBD) of nuclear receptor (NR): Nuclear receptors form a superfamily of ligand-activated transcription regulators, which regulate various physiological functions in metazoans, from development, reproduction, to homeostasis and metabolism. The superfamily contains not only receptors for known ligands but also orphan receptors for which ligands do not exist or have not been identified. The members of the family include receptors of steroids, thyroid hormone, retinoids, cholesterol by-products, lipids and heme. With few exceptions, NRs share a common structural organization with a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 179 DLTEKIRKAHQETFPSLCQLGKYTTNSSADHRVRLDLGLWDKFSELATKCIIKIVEFAKRLPGFTGLTIADQITLLKAAC 258
Cdd:cd06937    1 DLITKVRKAHQETFPSLCQLGKYTTNSSADQRVRLDLGLWDKFSELSTKCIIKIVEFAKRLPGFTTLTIADQITLLKAAC 80

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 259 LDIL----------------------------------------------LLPLEMDDTETGLLSAICLICGDRQDLEEP 292
Cdd:cd06937   81 LDILilrictrytpeqdtmtfsdgltlnrtqmhnagfgpltdlvftfanqLLPLEMDDTEIGLLSAICLICGDRQDLEEP 160

                        170       180       190       200       210       220       230
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 590122042 293 TKVDKLQEPLLEALKIYIRKRRPSKPHMFPKILMKITDLRSISAKGAERVITLKMEIPGSMPPLIQEMLEN 363
Cdd:cd06937  161 DRVEKLQEPLLEALKIYARKRRPDKPHMFPKMLMKITDLRSISAKGAERVITLKMEIPGPMPPLISEMLEN 231

The ligand binding domain (LBD) of retinoic acid receptor (RAR), a members of the nuclear receptor superfamily; The ligand binding domain (LBD) of retinoic acid receptor (RAR): Retinoic acid receptors are members of the nuclear receptor (NR) superfamily of ligand-regulated transcription factors. RARs mediate the biological effect of retinoids, including both naturally dietary vitamin A (retinol) metabolites and active synthetic analogs. Retinoids play key roles in a wide variety of essential biological processes, such as vertebrate embryonic morphogenesis and organogenesis, differentiation and apoptosis, and homeostasis. RARs function as heterodimers with retinoic X receptors by binding to specific RAR response elements (RAREs) found in the promoter regions of retinoid target genes. In the absence of ligand, the RAR-RXR heterodimer recruits the corepressor proteins NCoR or AMRT, and associated factors such as histone deacetylases or DNA-methyltransferases, leading to an inactive condensed chromatin structure, preventing transcription. Upon ligand binding, the corepressors are released, and coactivator complexes such as histone acetyltransferase or histone arginine methyltransferases are recruited to activate transcription. There are three RAR subtypes (alpha, beta, gamma), originating from three distinct genes. For each subtype, several isoforms exist that differ in their N-terminal region, allowing retinoids to exert their pleiotropic effects. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, retinoic acid receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 179 DLTEKIRKAHQETFPSLCQLGKYTTNSSADHRVRLDLGLWDKFSELATKCIIKIVEFAKRLPGFTGLTIADQITLLKAAC 258
Cdd:cd06937    1 DLITKVRKAHQETFPSLCQLGKYTTNSSADQRVRLDLGLWDKFSELSTKCIIKIVEFAKRLPGFTTLTIADQITLLKAAC 80

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 259 LDIL----------------------------------------------LLPLEMDDTETGLLSAICLICGDRQDLEEP 292
Cdd:cd06937   81 LDILilrictrytpeqdtmtfsdgltlnrtqmhnagfgpltdlvftfanqLLPLEMDDTEIGLLSAICLICGDRQDLEEP 160

                        170       180       190       200       210       220       230
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 590122042 293 TKVDKLQEPLLEALKIYIRKRRPSKPHMFPKILMKITDLRSISAKGAERVITLKMEIPGSMPPLIQEMLEN 363
Cdd:cd06937  161 DRVEKLQEPLLEALKIYARKRRPDKPHMFPKMLMKITDLRSISAKGAERVITLKMEIPGPMPPLISEMLEN 231

Zinc finger, C4 type (two domains); In nearly all cases, this is the DNA binding domain of a nuclear hormone receptor. The alignment contains two Zinc finger domains that are too dissimilar to be aligned with each other.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 590122042   80 PCFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMS 147
Cdd:pfam00105   1 LCKVCGDKASGYHYGVLTCEGCKGFFRRSIQKNIVYTCKFNKDCVIDKRNRNRCQYCRLKKCLEVGMS 68

Ligand binding domain of hormone receptors;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042   225 ATKCIIKIVEFAKRLPGFTGLTIADQITLLKAACLDILLL---------------------------------------- 264
Cdd:smart00430   1 AERQLLLTVEWAKSFPGFRELSLEDQIVLLKSFWFELLLLelayrsvklkkelllapdgtyirpdavlelrklfspfldr 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042   265 ----------PLEMDDTETGLLSAICLICGDRQDLEEPTK--VDKLQEPLLEALKIYIRKRRPSKPHM-FPKILMKITDL 331
Cdd:smart00430  81 ilselvkplrELKLDDEEYALLKAIVLFNPAVPGLSEEGKeiVEKLQEKYANALHDYYLKNYPMNYPGrFAKLLLILPEL 160

                   ...
gi 590122042   332 RSI 334
Cdd:smart00430 161 RKI 163

The ligand binding domain (LBD) of retinoic acid receptor (RAR), a members of the nuclear receptor superfamily; The ligand binding domain (LBD) of retinoic acid receptor (RAR): Retinoic acid receptors are members of the nuclear receptor (NR) superfamily of ligand-regulated transcription factors. RARs mediate the biological effect of retinoids, including both naturally dietary vitamin A (retinol) metabolites and active synthetic analogs. Retinoids play key roles in a wide variety of essential biological processes, such as vertebrate embryonic morphogenesis and organogenesis, differentiation and apoptosis, and homeostasis. RARs function as heterodimers with retinoic X receptors by binding to specific RAR response elements (RAREs) found in the promoter regions of retinoid target genes. In the absence of ligand, the RAR-RXR heterodimer recruits the corepressor proteins NCoR or AMRT, and associated factors such as histone deacetylases or DNA-methyltransferases, leading to an inactive condensed chromatin structure, preventing transcription. Upon ligand binding, the corepressors are released, and coactivator complexes such as histone acetyltransferase or histone arginine methyltransferases are recruited to activate transcription. There are three RAR subtypes (alpha, beta, gamma), originating from three distinct genes. For each subtype, several isoforms exist that differ in their N-terminal region, allowing retinoids to exert their pleiotropic effects. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, retinoic acid receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 179 DLTEKIRKAHQETFPSLCQLGKYTTNSSADHRVRLDLGLWDKFSELATKCIIKIVEFAKRLPGFTGLTIADQITLLKAAC 258
Cdd:cd06937    1 DLITKVRKAHQETFPSLCQLGKYTTNSSADQRVRLDLGLWDKFSELSTKCIIKIVEFAKRLPGFTTLTIADQITLLKAAC 80

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 259 LDIL----------------------------------------------LLPLEMDDTETGLLSAICLICGDRQDLEEP 292
Cdd:cd06937   81 LDILilrictrytpeqdtmtfsdgltlnrtqmhnagfgpltdlvftfanqLLPLEMDDTEIGLLSAICLICGDRQDLEEP 160

                        170       180       190       200       210       220       230
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 590122042 293 TKVDKLQEPLLEALKIYIRKRRPSKPHMFPKILMKITDLRSISAKGAERVITLKMEIPGSMPPLIQEMLEN 363
Cdd:cd06937  161 DRVEKLQEPLLEALKIYARKRRPDKPHMFPKMLMKITDLRSISAKGAERVITLKMEIPGPMPPLISEMLEN 231

DNA-binding domain of nuclear receptors is composed of two C4-type zinc fingers; DNA-binding domain of nuclear receptors is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. It interacts with a specific DNA site upstream of the target gene and modulates the rate of transcriptional initiation. Nuclear receptors form a superfamily of ligand-activated transcription regulators, which regulate various physiological functions, from development, reproduction, to homeostasis and metabolism in animals (metazoans). The family contains not only receptors for known ligands but also orphan receptors for which ligands do not exist or have not been identified. NRs share a common structural organization with a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD). Most nuclear receptors bind as homodimers or heterodimers to their target sites, which consist of two hexameric half-sites. Specificity is determined by the half-site sequence, the relative orientation of the half-sites and the number of spacer nucleotides between the half-sites. However, a growing number of nuclear receptors have been reported to bind to DNA as monomers.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVR 152
Cdd:cd06916    1 CAVCGDKASGYHYGVLTCEGCKGFFRRSVRRNLEYTCPAGGNCVIDKRNRNRCQACRLKKCLAVGMRKEAVR 72

Zinc finger, C4 type (two domains); In nearly all cases, this is the DNA binding domain of a nuclear hormone receptor. The alignment contains two Zinc finger domains that are too dissimilar to be aligned with each other.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 590122042   80 PCFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMS 147
Cdd:pfam00105   1 LCKVCGDKASGYHYGVLTCEGCKGFFRRSIQKNIVYTCKFNKDCVIDKRNRNRCQYCRLKKCLEVGMS 68

DNA-binding domain of thyroid hormone receptors (TRs) is composed of two C4-type zinc fingers; DNA-binding domain of thyroid hormone receptors (TRs) is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. TR interacts with the thyroid response element, which is a DNA site with direct repeats of the consensus sequence 5'-AGGTCA-3' separated by one to five base pairs, upstream of target genes and modulates the rate of transcriptional initiation. Thyroid hormone receptor (TR) mediates the actions of thyroid hormones, which play critical roles in growth, development, and homeostasis in mammals. They regulate overall metabolic rate, cholesterol and triglyceride levels, and heart rate, and affect mood. TRs are expressed from two separate genes (alpha and beta) in human and each gene generates two isoforms of the receptor through differential promoter usage or splicing. TRalpha functions in the heart to regulate heart rate and rhythm and TRbeta is active in the liver and other tissues. The unliganded TRs function as transcription repressors, by binding to thyroid hormone response elements (TRE) predominantly as homodimers, or as heterodimers with retinoid X-receptors (RXR), and being associated with a complex of proteins containing corepressor proteins. Ligand binding promotes corepressor dissociation and binding of a coactivator to activate transcription. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, TR has a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042  80 PCFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDRNKKK 159
Cdd:cd06961    1 PCVVCGDKATGYHYRCITCEGCKGFFRRTVQKKLSYSCKGEGKCEIDKVTRNQCQECRFKKCIAVGMAKDLVLDDRKRGA 80

                 .
gi 590122042 160 K 160
Cdd:cd06961   81 K 81

DNA-binding domain of Retinoid-related orphan receptors (RORs) is composed of two C4-type zinc fingers; DNA-binding domain of Retinoid-related orphan receptors (RORs) is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which coordinates a single zinc atom. ROR interacts with specific DNA sites upstream of the target gene and modulates the rate of transcriptional initiation. RORS are key regulators of many physiological processes during embryonic development. RORs bind as monomers to specific ROR response elements (ROREs) consisting of the consensus core motif AGGTCA preceded by a 5-bp A/T-rich sequence. There are three subtypes of retinoid-related orphan receptors (RORs), alpha, beta, and gamma, which differ only in N-terminal sequence and are distributed in distinct tissues. RORalpha plays a key role in the development of the cerebellum particularly in the regulation of the maturation and survival of Purkinje cells. RORbeta expression is largely restricted to several regions of the brain, the retina, and pineal gland. RORgamma is essential for lymph node organogenesis. Recently, it has been suggested that cholesterol or a cholesterol derivative are the natural ligands of RORalpha. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, retinoid-related orphan receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042  80 PCFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDRNKKK 159
Cdd:cd06968    7 PCKICGDKSSGIHYGVITCEGCKGFFRRSQQNNVSYSCPRQKNCLIDRTNRNRCQHCRLQKCLALGMSRDAVKFGRMSKK 86

                 .
gi 590122042 160 K 160
Cdd:cd06968   87 Q 87

The DNA-binding domain of Lrh-1 like nuclear receptor family like is composed of two C4-type zinc fingers; The DNA-binding domain of Lrh-1 like nuclear receptor family like is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. This domain interacts with specific DNA sites upstream of the target gene and modulates the rate of transcriptional initiation. This nuclear receptor family includes at least three subgroups of receptors that function in embryo development and differentiation, and other processes. FTZ-F1 interacts with the cis-acting DNA motif of ftz gene, which is required at several stages of development. Particularly, FTZ-F1 regulated genes are strongly linked to steroid biosynthesis and sex-determination; LRH-1 is a regulator of bile-acid homeostasis, steroidogenesis, reverse cholesterol transport and the initial stages of embryonic development; SF-1 is an essential regulator of endocrine development and function and is considered a master regulator of reproduction; SF-1 functions cooperatively with other transcription factors to modulate gene expression. Phospholipids have been identified as potential ligand for LRH-1 and steroidogenic factor-1 (SF-1). However, the ligand for FTZ-F1 has not yet been identified. Most nuclear receptors function as homodimer or heterodimers. However, LRH-1 and SF-1 bind to DNA as monomers. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, receptors in this family have a central well conserved DNA-binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDR 155
Cdd:cd07167    1 CPVCGDKVSGYHYGLLTCESCKGFFKRTVQNKKRYTCIENQNCQIDKTQRKRCPYCRFQKCLSVGMKLEAVRADR 75

DNA-binding domain of the TR2 and TR4 (human testicular receptor 2 and 4) is composed of two C4-type zinc fingers; DNA-binding domain of the TR2 and TR4 (human testicular receptor 2 and 4) is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which coordinates a single zinc atom. TR2 and TR4 interact with specific DNA sites upstream of the target gene and modulate the rate of transcriptional initiation. TR4 and TR2 are orphan nuclear receptors; the physiological ligand is as yet unidentified. TR2 is abundantly expressed in the androgen-sensitive prostate. TR4 transcripts are expressed in many tissues, including central nervous system, adrenal gland, spleen, thyroid gland, and prostate. It has been shown that human TR2 binds to a wide spectrum of natural hormone response elements (HREs) with distinct affinities suggesting that TR2 may cross-talk with other gene expression regulation systems. The genes responding to TR2 or TR4 include genes that are regulated by retinoic acid receptor, vitamin D receptor, and peroxisome proliferator-activated receptor. TR4/2 binds to HREs as dimers. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, TR2-like receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042  76 RVYKPCFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDR 155
Cdd:cd06967    1 QPVELCVVCGDKASGRHYGAVSCEGCKGFFKRSIRKNLGYSCRGSKDCVINKHHRNRCQYCRLQKCLAMGMKSDSVQCER 80

The ligand binding domain of Liver X receptors, a family of nuclear receptors of ligand-activated transcription factors; The ligand binding domain of Liver X receptors: Liver X receptors (LXRs) belong to a family of nuclear receptors of ligand-activated transcription factors. LXRs operate as cholesterol sensors which protect from cholesterol overload by stimulating reverse cholesterol transport from peripheral tissues to the liver and its excretion in the bile. Oxidized cholesterol derivatives or oxysterols were identified as specific ligands for LXRs. Upon ligand binding a conformational change leads to recruitment of co-factors, which stimulates expression of target genes. Among the LXR target genes are several genes involved in cholesterol efflux from peripheral tissues such as the ATP-binding-cassette transporters ABCA1, ABCG1 and ApoE. There are two LXR isoforms in mammals, LXRalpha and LXRbeta. LXRalpha is expressed mainly in the liver, intestine, kidney, spleen, and adipose tissue, whereas LXRbeta is ubiquitously expressed at lower level. Both LXRalpha and LXRbeta function as heterodimers with the retinoid X receptor (RX R) which may be activated by either LXR ligands or 9-cis retinoic acid, a specific RXR ligand. The LXR/RXR complex binds to a liver X receptor response element (LXRE) in the promoter region of target genes. LXR has typical NR modular structure with a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and the ligand binding domain (LBD) at the C-terminal.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 221 FSELATKCIIKIVEFAKRLPGFTGLTIADQITLLKAACLDILLL------------------------------------ 264
Cdd:cd06954   48 FTELAILSVQEIVDFAKQLPGFLTLTREDQIALLKASTIEVMLLetarrynpeseaitflkdfpysrddfaraglqvefi 127

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 265 -----------PLEMDDTETGLLSAICLICGDRQDLEEPTKVDKLQEPLLEALKIYIRKRRPSKPHMFPKILMKITDLRS 333
Cdd:cd06954  128 npifefsksmrELQLDDAEYALLIAINIFSADRPNVQDHHRVERLQETYVEALHSYIKIKRPSDRLMFPRMLMKLVSLRT 207

                        170       180
                 ....*....|....*....|....*..
gi 590122042 334 ISAKGAERVITLKMEiPGSMPPLIQEM 360
Cdd:cd06954  208 LSSVHSEQVFALRLQ-DKKLPPLLSEI 233

DNA-binding domain of ecdysone-induced DHR4 orphan nuclear receptor is composed of two C4-type zinc fingers; DNA-binding domain of ecdysone-induced DHR4 orphan nuclear receptor is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which coordinates a single zinc atom. This domain interacts with specific DNA sites upstream of the target gene and modulates the rate of transcriptional initiation. Ecdysone-induced orphan receptor DHR4 is a member of the nuclear receptor family. DHR4 is expressed during the early Drosophila larval development and is induced by ecdysone. DHR4 coordinates growth and maturation in Drosophila by mediating endocrine response to the attainment of proper body size during larval development. Mutations in DHR4 result in shorter larval development which translates into smaller and lighter flies. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, DHR4 has a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042  76 RVYKPCFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDR 155
Cdd:cd07168    4 ESPKLCSICEDKATGLHYGIITCEGCKGFFKRTVQNKRVYTCVGDGRCEITKAQRNRCQYCRFRKCIRKGMMLAAVREDR 83

The DNA-binding domain of peroxisome proliferator-activated receptors (PPAR) like nuclear receptor family; The DNA-binding domain of peroxisome proliferator-activated receptors (PPAR) like nuclear receptor family is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. These domains interact with specific DNA sites upstream of the target gene and modulate the rate of transcriptional initiation. This family includes three known types of nuclear receptors: peroxisome proliferator-activated receptors (PPAR), REV-ERB receptors and Drosophila ecdysone-induced protein 78 (E78). Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, PPAR-like receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYT-CHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVR 152
Cdd:cd07158    1 CKVCGDKASGFHYGVHSCEGCKGFFRRTIQHNLTYRrCLNGGKCVIQRKNRNRCQYCRFKKCLSVGMSRNAVR 73

DNA-binding domain of retinoid X receptor (RXR) is composed of two C4-type zinc fingers; DNA-binding domain of retinoid X receptor (RXR) is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. RXR functions as a DNA binding partner by forming heterodimers with other nuclear receptors including CAR, FXR, LXR, PPAR, PXR, RAR, TR, and VDR. All RXR heterodimers preferentially bind response elements composed of direct repeats of two AGGTCA sites with a 1-5 bp spacer. RXRs can play different roles in these heterodimers. RXR acts either as a structural component of the heterodimer complex, required for DNA binding but not acting as a receptor, or as both a structural and a functional component of the heterodimer, allowing 9-cis RA to signal through the corresponding heterodimer. In addition, RXR can also form homodimers, functioning as a receptor for 9-cis RA, independently of other nuclear receptors. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, RXR has a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDR 155
Cdd:cd06956    3 CAICGDRASGKHYGVYSCEGCKGFFKRTVRKDLTYTCRDNKDCLIDKRQRNRCQYCRYQKCLAMGMKREAVQEER 77

DNA-binding domain of Tailless (TLX) is composed of two C4-type zinc fingers; DNA-binding domain of Tailless (TLX) is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. TLX interacts with specific DNA sites upstream of the target gene and modulates the rate of transcriptional initiation. TLX is an orphan receptor that is expressed by neural stem/progenitor cells in the adult brain of the subventricular zone (SVZ) and the dentate gyrus (DG). It plays a key role in neural development by promoting cell cycle progression and preventing apoptosis in the developing brain. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, TLX has a central well conserved DNA-binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042  80 PCFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDK--NCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDRNK 157
Cdd:cd07163    8 PCKVCGDRSSGKHYGIYACDGCSGFFKRSIRRNRQYVCKSKGqgGCPVDKTHRNQCRACRLKKCFEVGMNKDAVQHERGP 87

                 ..
gi 590122042 158 KK 159
Cdd:cd07163   88 RN 89

DNA-binding domain of the photoreceptor cell-specific nuclear receptor (PNR) like proteins is composed of two C4-type zinc fingers; DNA-binding domain of the photoreceptor cell-specific nuclear receptor (PNR) like proteins is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. PNR interacts with specific DNA sites upstream of the target gene and modulates the rate of transcriptional initiation. PNR is a member of nuclear receptor superfamily of the ligand-activated transcription factors. PNR is expressed only in the outer layer of retinal photoreceptor cells. It may be involved in the signaling pathway regulating photoreceptor differentiation and/or maintenance. It most likely binds to DNA as a homodimer. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, PNR has a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDR 155
Cdd:cd07164    1 CRVCGDRASGKHYGVPSCDGCRGFFKRSIRRNLAYVCKENGSCVVDVARRNQCQACRFKKCLQVNMNRDAVQHER 75

The DNA-binding domain of the photoreceptor cell-specific nuclear receptor (PNR) nuclear receptor-like family; The DNA-binding domain of the photoreceptor cell-specific nuclear receptor (PNR) nuclear receptor-like family is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which coordinates a single zinc atom. PNR interacts with specific DNA sites upstream of the target gene and modulates the rate of transcriptional initiation. This family includes nuclear receptor Tailless (TLX), photoreceptor cell-specific nuclear receptor (PNR) and related receptors. TLX is an orphan receptor that plays a key role in neural development by regulating cell cycle progression and exit of neural stem cells in the developing brain. PNR is expressed only in the outer layer of retinal photoreceptor cells. It may be involved in the signaling pathway regulating photoreceptor differentiation and/or maintenance. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, PNR-like receptors have a central well-conserved DNA-binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHR-DKNCVINKVTRNRCQYCRLQKCFEVGMSKESVR 152
Cdd:cd07154    1 CKVCGDRSSGKHYGVYACDGCSGFFKRSIRRNLLYTCKAgNGSCVVDKARRNQCQACRLKKCLEVSMNKDAVQ 73

The ligand binding domain of Drosophila ecdysone-induced protein 78, a member of the nuclear receptor superfamily; The ligand binding domain (LBD) of Drosophila ecdysone-induced protein 78 (E78) like: Drosophila ecdysone-induced protein 78 (E78) is a transcription factor belonging to the nuclear receptor superfamily. E78 is a product of the ecdysone-inducible gene found in an early late puff locus at position 78C during the onset of Drosophila metamorphosis. Two isoforms of E78, E78A and E78B, are expressed from two nested transcription units. An E78 orthologue from the Platyhelminth Schistosoma mansoni (SmE78) has also been identified. It is the first E78 orthologue known outside of the molting animals--the Ecdysozoa. SmE78 may be involved in transduction of an ecdysone signal in S. mansoni, consistent with its function in Drosophila. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, E78-like receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 217 LWDKFSELATKCIIKIVEFAKRLPGFTGLTIADQITLLKAACLDILLL-------------------------------- 264
Cdd:cd06941    3 LWQQLSEALTPSVQRVVEFAKRIPGFCDLSQDDQLLLIKAGFFEVWLVrisrlinsksgsitfddgisisrqqldiiyds 82

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 265 --------------PLEMDDTETGLLSAICLICGDRQDLEEPTKVDKLQEPLLEALKIYIRKRRPSKPHMFPKILMKITD 330
Cdd:cd06941   83 dfvkalfefsdsfnSLGLSDTEVALFCAVVLLSPDRIGLSEPKKVAILQDRVLEALKVQVSRNRPAEAQLFASLLMKIPE 162

                        170       180       190
                 ....*....|....*....|....*....|...
gi 590122042 331 LRSISAKGAERVITLKMEIPG-SMPPLIQEMLE 362
Cdd:cd06941  163 LRSIGAKHQMHLDWYRVNWPLlRLPPLFAEIYD 195

The DNA-binding domain of vitamin D receptors (VDR) like nuclear receptor family is composed of two C4-type zinc fingers; The DNA-binding domain of vitamin D receptors (VDR) like nuclear receptor family is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. This domain interacts with specific DNA site upstream of the target gene and modulates the rate of transcriptional initiation. This family includes three types of nuclear receptors: vitamin D receptors (VDR), constitutive androstane receptor (CAR) and pregnane X receptor (PXR). VDR regulates calcium metabolism, cellular proliferation and differentiation. PXR and CAR function as sensors of toxic byproducts of cell metabolism and of exogenous chemicals, to facilitate their elimination. The DNA binding activity is regulated by their corresponding ligands. VDR is activated by Vitamin D; CAR and PXR respond to a diverse array of chemically distinct ligands, including many endogenous compounds and clinical drugs. Like other nuclear receptors, xenobiotic receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESV 151
Cdd:cd07156    1 CGVCGDRATGYHFNAMTCEGCKGFFRRSMKRKARFTCPFNGDCEITKDNRRHCQACRLKKCLDIGMKKEMI 71

DNA-binding domain of the photoreceptor cell-specific nuclear receptor (PNR) is composed of two C4-type zinc fingers; DNA-binding domain of the photoreceptor cell-specific nuclear receptor (PNR) is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. PNR interacts with specific DNA sites upstream of the target gene and modulates the rate of transcriptional initiation. PNR is a member of the nuclear receptor superfamily of the ligand-activated transcription factors. PNR is expressed only in the outer layer of retinal photoreceptor cells. It may be involved in the signaling pathway regulating photoreceptor differentiation and/or maintenance. It most likely binds to DNA as a homodimer. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, PNR has a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDK-NCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDRNKK 158
Cdd:cd06970    9 CRVCGDTSSGKHYGIYACNGCSGFFKRSVRRKLIYRCQAGTgMCPVDKAHRNQCQACRLKKCLQAGMNKDAVQNERQPR 87

The ligand binding domain of peroxisome proliferator-activated receptors; The ligand binding domain (LBD) of peroxisome proliferator-activated receptors (PPAR): Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily of ligand-activated transcription factors. PPARs play important roles in regulating cellular differentiation, development and lipid metabolism. Activated PPAR forms a heterodimer with the retinoid X receptor (RXR) that binds to the hormone response element located upstream of the peroxisome proliferator responsive genes and interacts with co-activators. There are three subtypes of peroxisome proliferator activated receptors, alpha, beta (or delta), and gamma, each with a distinct tissue distribution. Several essential fatty acids, oxidized lipids and prostaglandin J derivatives can bind and activate PPAR. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, PPAR has a central well conserved DNA binding domain (DBD), a variable N-terminal regulatory domain, a flexible hinge a nd a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 229 IIKIVEFAKRLPGFTGLTIADQITLLKAACL-------------DILLLP------------------------------ 265
Cdd:cd06932   76 IRELTEFAKSLPGFRNLDLNDQVTLLKYGVHeviftmlaslynkDGLLFPegngyvtrefleslrkpfcdimepkfefae 155

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 266 ----LEMDDTETGLLSAICLICGDRQDLEEPTKVDKLQEPLLEALKIYIRKRRPSKPHMFPKILMKITDLRSISAKGAER 341
Cdd:cd06932  156 kfnaLELTDSELALFCAVIILSPDRPGLINRKPVERIQEHVLQALELQLKKNHPDSPQLFAKLLQKMVDLRQLVTDHVQM 235

                        170
                 ....*....|....*....
gi 590122042 342 VITLKM-EIPGSMPPLIQE 359
Cdd:cd06932  236 VQQIKKtETDASLPPLLQE 254

The DNA-binding domain of Ecdysone receptor (EcR) like nuclear receptor family is composed of two C4-type zinc fingers; The DNA-binding domain of Ecdysone receptor (EcR) like nuclear receptor family is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. EcR interacts with specific DNA sites upstream of the target gene and modulates the rate of transcriptional initiation. This family includes three types of nuclear receptors: Ecdysone receptor (EcR), Liver X receptor (LXR) and Farnesoid X receptor (FXR). The DNA binding activity is regulated by their corresponding ligands. The ligands for EcR are ecdysteroids; LXR is regulated by oxidized cholesterol derivatives or oxysterols; and bile acids control FXR's activities. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, EcR-like receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESV 151
Cdd:cd06959    2 CVVCGDKASGFHYGVLSCEGCKGFFRRSVTKGAVYACKFGNKCEMDMYMRRKCQECRLRKCKAAGMRPDCL 72

DNA-binding domain of pregnane X receptor (PXRs) is composed of two C4-type zinc fingers; DNA-binding domain (DBD)of pregnane X receptor (PXR) is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. PXR DBD interacts with the PXR response element, a perfect repeat of two AGTTCA motifs with a 4 bp spacer upstream of the target gene, and modulates the rate of transcriptional initiation. The pregnane X receptor (PXR) is a ligand-regulated transcription factor that responds to a diverse array of chemically distinct ligands, including many endogenous compounds and clinical drugs. PXR functions as a heterodimer with retinoic X receptor-alpha (RXRa) and binds to a variety of promoter regions of a diverse set of target genes involved in the metabolism, transport, and ultimately, elimination of these molecules from the body. Like other nuclear receptors, PXR has a central well conserved DNA-binding domain, a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDRNKKKK 160
Cdd:cd07162    2 CRVCGDRATGYHFNAMTCEGCKGFFRRAMKRNARLCCPFQKGCVITKSNRRQCQACRLRKCLSIGMKKELIMSDEAVEKR 81

DNA-binding domain of Farnesoid X receptor (FXR) family is composed of two C4-type zinc fingers; DNA-binding domain of Farnesoid X receptor (FXR) family is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. FXR interacts with specific DNA sites upstream of the target gene and modulates the rate of transcriptional initiation. FXR is a member of the nuclear receptor family of ligand activated transcription factors. Bile acids are endogenous ligands for FXRs. Upon binding of a ligand, FXR binds to FXR response element (FXRE), which is an inverted repeat of TGACCT spaced by one nucleotide, either as a monomer or as a heterodimer with retinoid X receptor (RXR), to regulate the expression of various genes involved in bile acid, lipid, and glucose metabolism. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, FXR has a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042  81 CFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSKESVRNDRNKKKK 160
Cdd:cd06962    4 CVVCGDKASGYHYNALTCEGCKGFFRRSITKNAVYKCKNGGNCEMDMYMRRKCQECRLRKCKEMGMLAECLLTEIQCKSK 83

The ligand binding domain of Retinoid-related orphan receptors, of the nuclear receptor superfamily; The ligand binding domain (LBD) of Retinoid-related orphan receptors (RORs): Retinoid-related orphan receptors (RORs) are transcription factors belonging to the nuclear receptor superfamily. RORs are key regulators of many physiological processes during embryonic development. RORs bind as monomers to specific ROR response elements (ROREs) consisting of the consensus core motif AGGTCA preceded by a 5-bp A/T-rich sequence. Transcription regulation by RORs is mediated through certain corepressors, as well as coactivators. There are three subtypes of retinoid-related orphan receptors (RORs), alpha, beta, and gamma that differ only in N-terminal sequence and are distributed in distinct tissues. RORalpha plays a key role in the development of the cerebellum, particularly in the regulation of the maturation and survival of Purkinje cells. RORbeta expression is largely restricted to several regions of the brain, the retina, and pineal gland. RORgamma is essential for lymph node organogenesis. Recently, it has been su ggested that cholesterol or a cholesterol derivative is the natural ligand of RORalpha. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, retinoid-related orphan receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 176 ELDDLTEKIRKAHQETfpslCQLG-----------------KYTTNSSADHrvrldlgLWDKFSELATKCIIKIVEFAKR 238
Cdd:cd06939    2 ELEHLAQNICKAHLET----CQYLreelqqlrwktfsqeeiLAYQNKSREE-------MWQLCAEKITEAIQYVVEFAKR 70

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 239 LPGFTGLTIADQITLLKAACLDILL--------------------LPLEM------DD-------------------TET 273
Cdd:cd06939   71 IPGFMELCQNDQIVLLKAGSLEVVLvrmsrafnpsnntvlfdgkyAPIDLfkslgcDDlisavfdfakslcelklteDEI 150

                        170       180       190       200       210       220       230       240
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 274 GLLSAICLICGDRQDLEEPTKVDKLQEPLLEALKIYIRKRRPSKPHMfPKILMKITDLRSISAKGAERVITLKMEIPG-- 351
Cdd:cd06939  151 ALFSALVLISADRPGLQEKRKVEKLQQKIELALRHVLQKNHGDDTIL-TKLLAKMPTLRALCSLHMEKLQKFKQSYPDiv 229

                        250
                 ....*....|.
gi 590122042 352 --SMPPLIQEM 360
Cdd:cd06939  230 hlEFPPLYKEL 240

The ligand binding domain of REV-ERB receptors, members of the nuclear receptor superfamily; The ligand binding domain (LBD) of REV-ERB receptors: REV-ERBs are transcriptional regulators belonging to the nuclear receptor superfamily. They regulate a number of physiological functions including the circadian rhythm, lipid metabolism, and cellular differentiation. The LBD domain of REV-ERB is unusual in the nuclear receptor family by lacking the AF-2 region that is responsible for coactivator interaction. REV-ERBs act as constitutive repressors because of their inability to bind coactivators. REV-ERB receptors can bind to two classes of DNA response elements as either a monomer or heterodimer, indicating functional diversity. When bound to the DNA, they recruit corepressors (NcoR/histone deacetylase 3) to the promoter, resulting in repression of the target gene. The porphyrin heme has been demonstrated to function as a ligand for REV-ERB. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, REV-ERB receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 217 LWDKFSELATKCIIKIVEFAKRLPGFTGLTIADQITLLKAACLDILLL-------------------------------- 264
Cdd:cd06940   13 IWEEFSMSFTPAVREVVEFAKRIPGFRDLSQHDQVTLLKAGTFEVLMVrfaslfdakersvtflsgqkysvddlhsmgag 92

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 265 --------------PLEMDDTETGLLSAICLICGDRQDLEEPTKVDKLQEPLLEALKIYIRKRRPSKPHMFPKILMKITD 330
Cdd:cd06940   93 dllnsmfdfseklnSLQLSDEEMGLFTAVVLVSADRSGLENVNLVEALQETLIRALRTLIAKNHPNEPSIFTKLLLKLPD 172

                        170
                 ....*....|....*..
gi 590122042 331 LRSISAKGAERVITLKM 347
Cdd:cd06940  173 LRTLNNLHSEKLLAFKV 189

The first DNA-binding domain (DBD) of the 2DBD nuclear receptors is composed of two C4-type zinc fingers; The first DNA-binding domain (DBD) of the 2DBD nuclear receptors(NRs) is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. NRs interact with specific DNA sites upstream of the target gene and modulate the rate of transcriptional initiation. Theses proteins contain two DBDs in tandem, probably resulted from an ancient recombination event. The 2DBD-NRs are found only in flatworm species, mollusks and arthropods. Their biological function is unknown.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 590122042  79 KPCFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNM--IYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMSK 148
Cdd:cd07157    1 QTCQVCGEPAAGFHHGAYVCEACKKFFMRSSNAISftISECPNGGKCIIDKKNRTKCQACRYRKCLNVGMSL 72

DNA-binding domain of androgen receptor (AR) is composed of two C4-type zinc fingers; DNA-binding domain of androgen receptor (AR) is composed of two C4-type zinc fingers. Each zinc finger contains a group of four Cys residues which co-ordinates a single zinc atom. To regulate gene expression, AR interacts with a palindrome of the core sequence 5'-TGTTCT-3' with a 3-bp spacer. It also binds to the direct repeat 5'-TGTTCT-3' hexamer in some androgen controlled genes. AR is activated by the androgenic hormones, testosterone or dihydrotestosterone, which are responsible for primary and for secondary male characteristics, respectively. The primary mechanism of action of ARs is by direct regulation of gene transcription. The binding of androgen results in a conformational change in the androgen receptor which causes its transport from the cytosol into the cell nucleus, and dimerization. The receptor dimer binds to a hormone response element of AR regulated genes and modulates their expression. Another mode of action of androgen receptor is independent of their interactions with DNA. The receptor interacts directly with signal transduction proteins in the cytoplasm, causing rapid changes in cell function, such as ion transport. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, AR has a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 590122042  79 KPCFVCQDKSSGYHYGVSACEGCKGFFRRSIQKNMIYTCHRDKNCVINKVTRNRCQYCRLQKCFEVGMS 147
Cdd:cd07173    4 KTCLICGDEASGCHYGALTCGSCKVFFKRAAEGKQKYLCASRNDCTIDKFRRKNCPSCRLRKCFEAGMT 72

The ligand binding domain of Farnesoid X receptor:a member of the nuclear receptor superfamily of ligand-activated transcription factors; The ligand binding domain (LBD) of Farnesoid X receptor: Farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily of ligand-activated transcription factors. FXR is highly expressed in the liver, the intestine, the kidney, and the adrenals. FXR plays key roles in the regulation of bile acid, cholesterol, triglyceride, and glucose metabolism. Evidences show that it also regulates liver regeneration. Upon binding of ligands, such as bile acid, an endogenous ligand, FXRs bind to FXR response elements (FXREs) either as a monomer or as a heterodimer with retinoid X receptor (RXR), and regulate the expression of various genes involved in bile acid, lipid, and glucose metabolism. There are two FXR genes (FXRalpha and FXRbeta) in mammals. A single FXRalpha gene encodes four isoforms resulting from differential use of promoters and alternative splicing. FXRbeta is a functional receptor in mice, rats, rabbits and dogs, but is a pseudogene in humans and primates. Like other members of the nuclear receptor (NR) superfamily, farnesoid X receptors have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 221 FSELATKCIIKIVEFAKRLPGFTGLTIADQITLLKAACLDILLL----------------PLE----------------- 267
Cdd:cd06936   41 LTEMATSHVQVLVEFTKGLPGFETLDHEDQIALLKGSAVEAMFLrsaqiynkklpaghadLLEerirssgisdefitpmf 120

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 268 ----------MDDTETGLLSAICLICGDRQDLEEPTKVDKLQEPLLEALKIYIRKRRPSKPHMFPKILMKITDLRSISAK 337
Cdd:cd06936  121 nfyksmgelkMTQEEYALLTAITILFPDRPYLKDKEAVEKLQEPLLDLLQKFCKLYHPEDPQHFACLLGRLTELRTLNHH 200

                 ....*....
gi 590122042 338 GAERVITLK 346
Cdd:cd06936  201 HAEMLMSWK 209

The ligand binding domain of vitamin D receptors, a member of the nuclear receptor superfamily; The ligand binding domain of vitamin D receptors (VDR): VDR is a member of the nuclear receptor (NR) superfamily that functions as classical endocrine receptors. VDR controls a wide range of biological activities including calcium metabolism, cell proliferation and differentiation, and immunomodulation. VDR is a high affinity receptor for the biologically most active Vitamin D metabolite, 1alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3). The binding of the ligand to the receptor induces a conformational change of the ligand binding domain (LBD) with consequent dissociation of corepressors. Upon ligand binding, VDR forms heterodimer with the retinoid X receptor (RXR) that binds to vitamin D response elements (VDREs), recruits coactivators. This leads to the expression of a large number of genes. Approximately 200 human genes are considered to be primary targets of VDR and even more genes are regulated indirectly. Like other members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors, VDR has a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a flexible hinge and a C-terminal ligand binding domain (LBD).

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 170 SYEMTAELDDLTEKIRKAHQETFPSLCQLgkyttnssadhRVRLDLGLWDKFSELATKCIIKIVEFAKRLPGFTGLTIAD 249
Cdd:cd06933    2 SDEQQKIIDILLEAHHKTYDTTYSDFNKF-----------RPPVRLSMLPHLADLVSYSIQKVIGFAKMIPGFRDLTAED 70

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 590122042 250 QITLLKAACLDILLL----PLEMDD-----------------TETG---------------------------LLSAICL 281
Cdd:cd06933   71 QIALLKSSAIEVIMLrsnqSFSLDDmswtcgspdfkykvsdvTKAGhslelleplvkfqvglkklnlheeehvLLMAICI 150