DNA-binding domain of Signal Transducer and Activator of Transcription 1 (STAT1); This family consists of the DNA-binding domain (DBD) of the STAT1 proteins (Signal Transducer and Activator of Transcription 1, or Signal Transduction And Transcription 1). The DNA binding domain has an Ig-like fold. STAT1 plays an essential role in mediating responses to all types of interferons (IFN), transducing signals from cytoplasmic domains of transmembrane receptors into the nucleus where it regulates gene expression. Thus STAT1 is involved in modulating diverse cellular processes, such as antimicrobial activities, cell proliferation and cell death. STAT1 function is crucial in the innate and adaptive arm of immunity and protects from pathogen infections; phosphorylation of a critical tyrosine by Janus kinases (JAKs) leads to its activation and nuclear translocation, while phosphorylation of a critical serine is required for full transcriptional activation upon IFN stimulation and in response to cellular stress. Transcription of protein-encoding genes (including Stat1 itself) as well as expression of microRNAs (miRNAs) is regulated by activated STAT1. Animal studies have shown that STAT1 is generally considered a tumor suppressor but it can also act as a tumor promoter; its functions are not restricted to tumor cells, but extend to parts of the tumor microenvironment such as immune cells, endothelial cells. STAT1 abundance is a reliable marker for good prognosis in selected tumor types, but it can also correlate with disease progression. In head and neck cancer (HNC) patients, upregulation of STAT1-induced HLA class I enhances immunogenicity and clinical response to anti-EGFR mAb cetuximab therapy. In systemic juvenile idiopathic arthritis (sJIA) characterized by systemic inflammation and arthritis, STAT1 phosphorylation downstream of IFNs is impaired. It exerts anti-oncogenic activities through interferon-gamma and interferon-alpha. STAT1 may inhibit hepatocellular carcinoma cell growth by regulating p53-related cell cycling and apoptosis. Studies also show a significant correlation of high STAT1 activity with longer colorectal cancer patient overall survival. Recent studies have shown that STAT1 suppresses mouse mammary gland tumorigenesis by immune regulatory as well as tumor cell-specific functions of STAT1.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 319 FVVERQPCMPTHPQRPLVLKTGVQFTVKLRLLVKLQELNYNLKVKVLFDKDVNERNTVKGFRKFNILGTHTKVMNMEEST 398
Cdd:cd16845     1 FVVERQPCMPTHPQRPLVLKTGVQFTVKLRLLVKLQELNYQLKVKVLFDKDVTEKNTVKGFRKFNILGTNTKVMNMEEST 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 399 NGSLAAEFRHLQLKEQKNAGTRTNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPVVVISNVSQLPSGWASILWYNM 478
Cdd:cd16845    81 NGSLAAEFRHLQLKEQKNAGTRTNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPIVVISNVSQLPSGWASILWYNM 160

                  .
gi 1862755518 479 L 479
Cdd:cd16845   161 L 161

Src homology 2 (SH2) domain; In general, SH2 domains are involved in signal transduction; they bind pTyr-containing polypeptide ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites. They are present in a wide array of proteins including: adaptor proteins (Nck1, Crk, Grb2), scaffolds (Slp76, Shc, Dapp1), kinases (Src, Syk, Fps, Tec), phosphatases (Shp-1, Shp-2), transcription factors (STAT1), Ras signaling molecules (Ras-Gap), ubiquitination factors (c-Cbl), cytoskeleton regulators (Tensin), signal regulators (SAP), and phospholipid second messengers (PLCgamma), amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 559 WIESILELIKKHLLPLWNDGCIMGFISKERERALLKDQQPGTFLLRFSESSREGAITFTWVERSQNGGEPDFHAVEPYTK 638
Cdd:cd10372     1 WIESILELIKKHLLSLWNDGCIMGFISKERERALLKDQQPGTFLLRFSESSREGAITFTWVERSQNGGEPDFHAVEPYTK 80

                          90
                  ....*....|....*..
gi 1862755518 639 KELSAVTFPDIIRNYKV 655
Cdd:cd10372    81 KELSAVTFPDIIRNYKV 97

DNA-binding domain of Signal Transducer and Activator of Transcription 1 (STAT1); This family consists of the DNA-binding domain (DBD) of the STAT1 proteins (Signal Transducer and Activator of Transcription 1, or Signal Transduction And Transcription 1). The DNA binding domain has an Ig-like fold. STAT1 plays an essential role in mediating responses to all types of interferons (IFN), transducing signals from cytoplasmic domains of transmembrane receptors into the nucleus where it regulates gene expression. Thus STAT1 is involved in modulating diverse cellular processes, such as antimicrobial activities, cell proliferation and cell death. STAT1 function is crucial in the innate and adaptive arm of immunity and protects from pathogen infections; phosphorylation of a critical tyrosine by Janus kinases (JAKs) leads to its activation and nuclear translocation, while phosphorylation of a critical serine is required for full transcriptional activation upon IFN stimulation and in response to cellular stress. Transcription of protein-encoding genes (including Stat1 itself) as well as expression of microRNAs (miRNAs) is regulated by activated STAT1. Animal studies have shown that STAT1 is generally considered a tumor suppressor but it can also act as a tumor promoter; its functions are not restricted to tumor cells, but extend to parts of the tumor microenvironment such as immune cells, endothelial cells. STAT1 abundance is a reliable marker for good prognosis in selected tumor types, but it can also correlate with disease progression. In head and neck cancer (HNC) patients, upregulation of STAT1-induced HLA class I enhances immunogenicity and clinical response to anti-EGFR mAb cetuximab therapy. In systemic juvenile idiopathic arthritis (sJIA) characterized by systemic inflammation and arthritis, STAT1 phosphorylation downstream of IFNs is impaired. It exerts anti-oncogenic activities through interferon-gamma and interferon-alpha. STAT1 may inhibit hepatocellular carcinoma cell growth by regulating p53-related cell cycling and apoptosis. Studies also show a significant correlation of high STAT1 activity with longer colorectal cancer patient overall survival. Recent studies have shown that STAT1 suppresses mouse mammary gland tumorigenesis by immune regulatory as well as tumor cell-specific functions of STAT1.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 319 FVVERQPCMPTHPQRPLVLKTGVQFTVKLRLLVKLQELNYNLKVKVLFDKDVNERNTVKGFRKFNILGTHTKVMNMEEST 398
Cdd:cd16845     1 FVVERQPCMPTHPQRPLVLKTGVQFTVKLRLLVKLQELNYQLKVKVLFDKDVTEKNTVKGFRKFNILGTNTKVMNMEEST 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 399 NGSLAAEFRHLQLKEQKNAGTRTNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPVVVISNVSQLPSGWASILWYNM 478
Cdd:cd16845    81 NGSLAAEFRHLQLKEQKNAGTRTNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPIVVISNVSQLPSGWASILWYNM 160

                  .
gi 1862755518 479 L 479
Cdd:cd16845   161 L 161

Src homology 2 (SH2) domain found in signal transducer and activator of transcription (STAT) 1 proteins; STAT1 is a member of the STAT family of transcription factors. STAT1 is involved in upregulating genes due to a signal by interferons. STAT1 forms homodimers or heterodimers with STAT3 that bind to the Interferon-Gamma Activated Sequence (GAS) promoter element in response to IFN-gamma stimulation. STAT1 forms a heterodimer with STAT2 that can bind Interferon Stimulated Response Element (ISRE) promoter element in response to either IFN-alpha or IFN-beta stimulation. Binding in both cases leads to an increased expression of ISG (Interferon Stimulated Genes). STAT1 has been shown to interact with protein kinase R, Src, IRF1, STAT3, MCM5, STAT2, CD117, Fanconi anemia, complementation group C, CREB-binding protein, Interleukin 27 receptor, alpha subunit, PIAS1, BRCA1, Epidermal growth factor receptor, PTK2, Mammalian target of rapamycin, IFNAR2, PRKCD, TRADD, C-jun, Calcitriol receptor, ISGF3G, and GNB2L1. STAT proteins mediate the signaling of cytokines and a number of growth factors from the receptors of these extracellular signaling molecules to the cell nucleus. STATs are specifically phosphorylated by receptor-associated Janus kinases, receptor tyrosine kinases, or cytoplasmic tyrosine kinases. The phosphorylated STAT molecules dimerize by reciprocal binding of their SH2 domains to the phosphotyrosine residues. These dimeric STATs translocate into the nucleus, bind to specific DNA sequences, and regulate the transcription of their target genes. However there are a number of unphosphorylated STATs that travel between the cytoplasm and nucleus and some STATs that exist as dimers in unstimulated cells that can exert biological functions independent of being activated. There are seven mammalian STAT family members which have been identified: STAT1, STAT2, STAT3, STAT4, STAT5 (STAT5A and STAT5B), and STAT6. There are 6 conserved domains in STAT: N-terminal domain (NTD), coiled-coil domain (CCD), DNA-binding domain (DBD), alpha-helical linker domain (LD), SH2 domain, and transactivation domain (TAD). NTD is involved in dimerization of unphosphorylated STATs monomers and for the tetramerization between STAT1, STAT3, STAT4 and STAT5 on promoters with two or more tandem STAT binding sites. It also plays a role in promoting interactions with transcriptional co-activators such as CREB binding protein (CBP)/p300, as well as being important for nuclear import and deactivation of STATs involving tyrosine de-phosphorylation. CCD interacts with other proteins, such as IFN regulatory protein 9 (IRF-9/p48) with STAT1 and c-JUN with STAT3 and is also thought to participate in the negative regulation of these proteins. Distinct genes are bound to STATs via their DBD domain. This domain is also involved in nuclear translocation of activated STAT1 and STAT3 phosphorylated dimers upon cytokine stimulation. LD links the DNA-binding and SH2 domains and is important for the transcriptional activation of STAT1 in response to IFN-gamma. It also plays a role in protein-protein interactions and has also been implicated in the constitutive nucleocytoplasmic shuttling of unphosphorylated STATs in resting cells. The SH2 domain is necessary for receptor association and tyrosine phosphodimer formation. Residues within this domain may be particularly important for some cellular functions mediated by the STATs as well as residues adjacent to this domain. The TAD interacts with several proteins, namely minichromosome maintenance complex component 5 (MCM5), breast cancer 1 (BRCA1) and CBP/p300. TAD also contains a modulatory phosphorylation site that regulates STAT activity and is necessary for maximal transcription of a number of target genes. The conserved tyrosine residue present in the C-terminus is crucial for dimerization via interaction with the SH2 domain upon the interaction of the ligand with the receptor. STAT activation by tyrosine phosphorylation also determines nuclear import and retention, DNA binding to specific DNA elements in the promoters of responsive genes, and transcriptional activation of STAT dimers. In addition to the SH2 domain there is a coiled-coil domain, a DNA binding domain, and a transactivation domain in the STAT proteins. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 559 WIESILELIKKHLLPLWNDGCIMGFISKERERALLKDQQPGTFLLRFSESSREGAITFTWVERSQNGGEPDFHAVEPYTK 638
Cdd:cd10372     1 WIESILELIKKHLLSLWNDGCIMGFISKERERALLKDQQPGTFLLRFSESSREGAITFTWVERSQNGGEPDFHAVEPYTK 80

                          90
                  ....*....|....*..
gi 1862755518 639 KELSAVTFPDIIRNYKV 655
Cdd:cd10372    81 KELSAVTFPDIIRNYKV 97

STAT protein, DNA binding domain; STAT proteins (Signal Transducers and Activators of Transcription) are a family of transcription factors that are specifically activated to regulate gene transcription when cells encounter cytokines and growth factors. This family represents the DNA binding domain of STAT, which has an ig-like fold. STAT proteins also include an SH2 domain pfam00017.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 332 QRPLVLKTGVQFTVKLRLLVKLQ---ELNYNLKVKVLFDKDVNERNTVKGFRKFNILG--THTKVMNMEESTNGSLAAEF 406
Cdd:pfam02864   2 QPPQVLKTNTKFSVTVRLLVGLPlniELNPQVKVKIVSEKQARELQQIKGFRKFNISGeiLNNKALLEYESQNGGLSAEF 81

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1862755518 407 RHLQLKEQKNAGtrtNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPVVVI 460
Cdd:pfam02864  82 RNLSLKEIKRGE---RKGSLSVTEEKFALLFETQFTLGGLVFDLWTLSLPVVVI 132

STAT protein, protein interaction domain; STAT proteins (Signal Transducers and Activators of Transcription) are a family of transcription factors that are specifically activated to regulate gene transcription when cells encounter cytokines and growth factors. STAT proteins also include an SH2 domain pfam00017.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518   4 SQWYELQQLDSKFLEQVHQLYDDSFPMEIRQYLAQWLEKQDWEHAANDVSFATIRFHDLLSQLDDQYSRFSLENNFLLQH 83
Cdd:pfam02865   1 SLWAQLQQLDGEALEQVQQLYGDHFPIEVRHYLAQWIESQDWEDAAQDESLATVLFHALLSELDSQASRFVQEDNFLLKH 80

                          90       100       110
                  ....*....|....*....|....*....|....*....
gi 1862755518  84 NIRKSKRNLQDNFQEDPIQMSMIIYSCLKEERKILENAQ 122
Cdd:pfam02865  81 KLREIAKNLQSRYQENPLELARIIRNCLREERRILQEAE 119

Src homology 2 domains; Src homology 2 domains bind phosphotyrosine-containing polypeptides via 2 surface pockets. Specificity is provided via interaction with residues that are distinct from the phosphotyrosine. Only a single occurrence of a SH2 domain has been found in S. cerevisiae.

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*
gi 1862755518  581 MGFISKERERALLKDQQPGTFLLRFSESSREG-AITFTWVERSQN 624
Cdd:smart00252   5 HGFISREEAEKLLKNEGDGDFLVRDSESSPGDyVLSVRVKGKVKH 49

DNA-binding domain of Signal Transducer and Activator of Transcription 1 (STAT1); This family consists of the DNA-binding domain (DBD) of the STAT1 proteins (Signal Transducer and Activator of Transcription 1, or Signal Transduction And Transcription 1). The DNA binding domain has an Ig-like fold. STAT1 plays an essential role in mediating responses to all types of interferons (IFN), transducing signals from cytoplasmic domains of transmembrane receptors into the nucleus where it regulates gene expression. Thus STAT1 is involved in modulating diverse cellular processes, such as antimicrobial activities, cell proliferation and cell death. STAT1 function is crucial in the innate and adaptive arm of immunity and protects from pathogen infections; phosphorylation of a critical tyrosine by Janus kinases (JAKs) leads to its activation and nuclear translocation, while phosphorylation of a critical serine is required for full transcriptional activation upon IFN stimulation and in response to cellular stress. Transcription of protein-encoding genes (including Stat1 itself) as well as expression of microRNAs (miRNAs) is regulated by activated STAT1. Animal studies have shown that STAT1 is generally considered a tumor suppressor but it can also act as a tumor promoter; its functions are not restricted to tumor cells, but extend to parts of the tumor microenvironment such as immune cells, endothelial cells. STAT1 abundance is a reliable marker for good prognosis in selected tumor types, but it can also correlate with disease progression. In head and neck cancer (HNC) patients, upregulation of STAT1-induced HLA class I enhances immunogenicity and clinical response to anti-EGFR mAb cetuximab therapy. In systemic juvenile idiopathic arthritis (sJIA) characterized by systemic inflammation and arthritis, STAT1 phosphorylation downstream of IFNs is impaired. It exerts anti-oncogenic activities through interferon-gamma and interferon-alpha. STAT1 may inhibit hepatocellular carcinoma cell growth by regulating p53-related cell cycling and apoptosis. Studies also show a significant correlation of high STAT1 activity with longer colorectal cancer patient overall survival. Recent studies have shown that STAT1 suppresses mouse mammary gland tumorigenesis by immune regulatory as well as tumor cell-specific functions of STAT1.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 319 FVVERQPCMPTHPQRPLVLKTGVQFTVKLRLLVKLQELNYNLKVKVLFDKDVNERNTVKGFRKFNILGTHTKVMNMEEST 398
Cdd:cd16845     1 FVVERQPCMPTHPQRPLVLKTGVQFTVKLRLLVKLQELNYQLKVKVLFDKDVTEKNTVKGFRKFNILGTNTKVMNMEEST 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 399 NGSLAAEFRHLQLKEQKNAGTRTNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPVVVISNVSQLPSGWASILWYNM 478
Cdd:cd16845    81 NGSLAAEFRHLQLKEQKNAGTRTNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPIVVISNVSQLPSGWASILWYNM 160

                  .
gi 1862755518 479 L 479
Cdd:cd16845   161 L 161

DNA-binding domain of Signal Transducer and Activator of Transcription 4 (STAT4); This family consists of the DNA-binding domain (DBD) of the STAT4 proteins (Signal Transducer and Activator of Transcription 4, or Signal Transduction And Transcription 4). The DNA binding domain has an Ig-like fold. STAT4 acts as the major signaling transducing STATs in response to interleukin-12 (IL-12) by inducing interferon-gamma (IFNg) , and is a central mediator in generating inflammation during protective immune responses and immune-mediated diseases. STAT4 is a critical regulator of Th1 differentiation and inflammatory disease. It is essential for the differentiation and function of many immune cells, including natural killer cells, dendritic cells, mast cells and T helper cells. STAT4-mediated signaling promotes the production of autoimmune-associated components, which are implicated in the pathogenesis of autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis and psoriasis, making STAT4 a promising therapeutic target for autoimmune diseases. Variations in STAT4 gene are linked to the development of systemic lupus erythematosus (SLE) in humans. STAT4 activation is detected in chronic liver diseases; polymorphism in STAT4 gene has been shown to be associated with the antiviral response in primary biliary cirrhosis (PBC), HCV-associated liver fibrosis, hepatocellular carcinoma (HCC), chronic hepatitis C and in drug-induced liver injury (DILI). STAT4 may inhibit HCC development by modulating HCC cell proliferation. Studies show that increased expression of STAT4 is positively correlated with the depth of invasion in colorectal cancer (CRC) patients, and the growth and invasion of CRC cells are repressed by inhibition of STAT4 expression, making STAT4 a promising therapeutic target for the treatment of CRC.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 319 FVVERQPCMPTHPQRPLVLKTGVQFTVKLRLLVKLQELNYNLKVKVLFDKDvnerntvkgfRKFNILGTHTKVMNMEEST 398
Cdd:cd16848     1 FVVERQPCMPTHPQRPMVLKTLIQFTVKLRLLIKLPELNYQIRVKATIDNN----------RRFVLCGTHVKAMNLEESV 70

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 399 NGSLAAEFRHLQLKEQK-NAGTRTNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPVVVISNVSQLPSGWASILWYN 477
Cdd:cd16848    71 NGSLSVEFRHLQPKEMKpSGGSKGNEGPHMVTEELHSISFETQFSLYGLTIDLETSSLPVVMISNVSQLPNAWASIIWYN 150

                  ..
gi 1862755518 478 ML 479
Cdd:cd16848   151 LL 152

DNA-binding domain of Signal Transducer and Activator of Transcription 3 (STAT3); This family consists of the DNA-binding domain (DBD) of the STAT3 proteins (Signal Transducer and Activator of Transcription 3, or Signal Transduction And Transcription 3). The DNA binding domain has an Ig-like fold. STAT3 plays key roles in vertebrate development and mature tissue function including control of inflammation and immunity. Mutations in human STAT3, especially in the DNA-binding and SH2 domains, are associated with diseases such as autoimmunity, immunodeficiency and cancer. STAT3 regulation is tightly controlled since either inactivation or hyperactivation results in disease. STAT3 activation is stimulated by several cytokines and growth factors, via diverse receptors. For example, IL-6 receptors depend on the tyrosine kinases JAK1 or JAK2, which associate with the cytoplasmic tail of gp130, and results in STAT3 phosphorylation, dimerization, and translocation to the nucleus; this leads to further IL-6 production and up-regulation of anti-apoptotic genes, thus promoting various cellular processes required for cancer progression. Other activators of STAT3 include IL-10, IL-23, and LPS activation of Toll-like receptors TLR4 and TLR9. STAT3 is constitutively activated in numerous cancer types, including over 40% of breast cancers. It has been shown to play a significant role in promoting acute myeloid leukemia (AML) through three mechanisms: promoting proliferation and survival, preventing AML differentiation to functional dendritic cells (DCs), and blocking T-cell function through other pathways. STAT3 also regulates mitochondrion functions, as well as gene expression through epigenetic mechanisms; its activation is induced by overexpression of Bcl-2 via an increase in mitochondrial superoxide. Thus, many of the regulators and functions of JAK-STAT3 in tumors are important therapeutic targets for cancer treatment.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 319 FVVERQPCMPTHPQRPLVLKTGVQFTVKLRLLVKLQELNYNLKVKVLFDKDVNERNTVKGFRKFNILGTHTKVMNMEEST 398
Cdd:cd16847     1 FVVERQPCMPMHPDRPLVIKTGVQFTTKVRLLVKFPELNYQLKIKVCIDKDSGDVAALRGSRKFNILGTNTKVMNMEESN 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 399 NGSLAAEFRHLQLKEQK--NAGTRTNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPVVVISNVSQLPSGWASILWY 476
Cdd:cd16847    81 NGSLSAEFKHLTLREQRcgNGGRANCDASLIVTEELHLITFETEVYHQGLKIDLETHSLPVVVISNICQMPNAWASILWY 160

                  ...
gi 1862755518 477 NML 479
Cdd:cd16847   161 NML 163

STAT protein, all-alpha domain; STAT proteins (Signal Transducers and Activators of Transcription) are a family of transcription factors that are specifically activated to regulate gene transcription when cells encounter cytokines and growth factors. STAT proteins also include an SH2 domain pfam00017.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 145 DSKVRNVKDKVMCIEHEIKSLEDLQDEYDFKCKTLQNREHETNGVAKSDQKQEQLLLKKMYLMLDNKRKEVVHKIIELLN 224
Cdd:pfam01017   1 EQRLEELRNRVQETEQDIKQLEDLQDEFDFKYKTLQKLQQERTESEDKELKQQKELLQQMLNALDQKRKEVLDKLKELLN 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 225 VTELTQNALINDELVEWKRRQQSACIGGPPNACLDQLQNWFTIVAESLQQVRQQLKKLEELEQKYTYEHDPITKNKQVLW 304
Cdd:pfam01017  81 LLETLQELLLDEELIEWKRRQQLACIGAPPNACLDQLQNWFTALAESLWQLRQQLKKLEELRQKLTYEGDPLTDGLPQLN 160

                  ....*..
gi 1862755518 305 DRTFSLF 311
Cdd:pfam01017 161 ERVTELL 167

STAT protein, DNA binding domain; STAT proteins (Signal Transducers and Activators of Transcription) are a family of transcription factors that are specifically activated to regulate gene transcription when cells encounter cytokines and growth factors. This family represents the DNA binding domain of STAT, which has an ig-like fold. STAT proteins also include an SH2 domain pfam00017.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 332 QRPLVLKTGVQFTVKLRLLVKLQ---ELNYNLKVKVLFDKDVNERNTVKGFRKFNILG--THTKVMNMEESTNGSLAAEF 406
Cdd:pfam02864   2 QPPQVLKTNTKFSVTVRLLVGLPlniELNPQVKVKIVSEKQARELQQIKGFRKFNISGeiLNNKALLEYESQNGGLSAEF 81

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1862755518 407 RHLQLKEQKNAGtrtNEGPLIVTEELHSLSFETQLCQPGLVIDLETTSLPVVVI 460
Cdd:pfam02864  82 RNLSLKEIKRGE---RKGSLSVTEEKFALLFETQFTLGGLVFDLWTLSLPVVVI 132

STAT protein, protein interaction domain; STAT proteins (Signal Transducers and Activators of Transcription) are a family of transcription factors that are specifically activated to regulate gene transcription when cells encounter cytokines and growth factors. STAT proteins also include an SH2 domain pfam00017.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518   4 SQWYELQQLDSKFLEQVHQLYDDSFPMEIRQYLAQWLEKQDWEHAANDVSFATIRFHDLLSQLDDQYSRFSLENNFLLQH 83
Cdd:pfam02865   1 SLWAQLQQLDGEALEQVQQLYGDHFPIEVRHYLAQWIESQDWEDAAQDESLATVLFHALLSELDSQASRFVQEDNFLLKH 80

                          90       100       110
                  ....*....|....*....|....*....|....*....
gi 1862755518  84 NIRKSKRNLQDNFQEDPIQMSMIIYSCLKEERKILENAQ 122
Cdd:pfam02865  81 KLREIAKNLQSRYQENPLELARIIRNCLREERRILQEAE 119

Src homology 2 (SH2) domain found in signal transducer and activator of transcription (STAT) 3 proteins; STAT3 encoded by this gene is a member of the STAT protein family. STAT3 mediates the expression of a variety of genes in response to cell stimuli, and plays a key role in many cellular processes such as cell growth and apoptosis. The small GTPase Rac1 regulates the activity of STAT3 and PIAS3 inhibits it. Three alternatively spliced transcript variants encoding distinct isoforms have been described. STAT 3 activation is required for self-renewal of embryonic stem cells (ESCs) and is essential for the differentiation of the TH17 helper T cells. Mutations in the STAT3 gene result in Hyperimmunoglobulin E syndrome and human cancers. STAT3 has been shown to interact with Androgen receptor, C-jun, ELP2, EP300, Epidermal growth factor receptor, Glucocorticoid receptor, HIF1A, Janus kinase 1, KHDRBS1, Mammalian target of rapamycin, MyoD, NDUFA13, NFKB1, Nuclear receptor coactivator 1, Promyelocytic leukemia protein, RAC1, RELA, RET proto-oncogene, RPA2, Src, STAT1, and TRIP10. STAT proteins mediate the signaling of cytokines and a number of growth factors from the receptors of these extracellular signaling molecules to the cell nucleus. STATs are specifically phosphorylated by receptor-associated Janus kinases, receptor tyrosine kinases, or cytoplasmic tyrosine kinases. The phosphorylated STAT molecules dimerize by reciprocal binding of their SH2 domains to the phosphotyrosine residues. These dimeric STATs translocate into the nucleus, bind to specific DNA sequences, and regulate the transcription of their target genes. However there are a number of unphosphorylated STATs that travel between the cytoplasm and nucleus and some STATs that exist as dimers in unstimulated cells that can exert biological functions independent of being activated. There are seven mammalian STAT family members which have been identified: STAT1, STAT2, STAT3, STAT4, STAT5 (STAT5A and STAT5B), and STAT6. There are 6 conserved domains in STAT: N-terminal domain (NTD), coiled-coil domain (CCD), DNA-binding domain (DBD), alpha-helical linker domain (LD), SH2 domain, and transactivation domain (TAD). NTD is involved in dimerization of unphosphorylated STATs monomers and for the tetramerization between STAT1, STAT3, STAT4 and STAT5 on promoters with two or more tandem STAT binding sites. It also plays a role in promoting interactions with transcriptional co-activators such as CREB binding protein (CBP)/p300, as well as being important for nuclear import and deactivation of STATs involving tyrosine de-phosphorylation. CCD interacts with other proteins, such as IFN regulatory protein 9 (IRF-9/p48) with STAT1 and c-JUN with STAT3 and is also thought to participate in the negative regulation of these proteins. Distinct genes are bound to STATs via their DBD domain. This domain is also involved in nuclear translocation of activated STAT1 and STAT3 phosphorylated dimers upon cytokine stimulation. LD links the DNA-binding and SH2 domains and is important for the transcriptional activation of STAT1 in response to IFN-gamma. It also plays a role in protein-protein interactions and has also been implicated in the constitutive nucleocytoplasmic shuttling of unphosphorylated STATs in resting cells. The SH2 domain is necessary for receptor association and tyrosine phosphodimer formation. Residues within this domain may be particularly important for some cellular functions mediated by the STATs as well as residues adjacent to this domain. The TAD interacts with several proteins, namely minichromosome maintenance complex component 5 (MCM5), breast cancer 1 (BRCA1) and CBP/p300. TAD also contains a modulatory phosphorylation site that regulates STAT activity and is necessary for maximal transcription of a number of target genes. The conserved tyrosine residue present in the C-terminus is crucial for dimerization via interaction with the SH2 domain upon the interaction of the ligand with the receptor. STAT activation by tyrosine phosphorylation also determines nuclear import and retention, DNA binding to specific DNA elements in the promoters of responsive genes, and transcriptional activation of STAT dimers. In addition to the SH2 domain there is a coiled-coil domain, a DNA binding domain, and a transactivation domain in the STAT proteins. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 552 KNFPFWLWIESILELIKKHLLPLWNDGCIMGFISKERERALLKDQQPGTFLLRFSESSREGAITFTWVERSQNgGEPDFH 631
Cdd:cd10374     4 KGFSFWVWLDNIIDLVKKYILALWNEGYIMGFISKERERAILSTKPPGTFLLRFSESSKEGGVTFTWVEKDIS-GKTQIQ 82

                          90       100
                  ....*....|....*....|....
gi 1862755518 632 AVEPYTKKELSAVTFPDIIRNYKV 655
Cdd:cd10374    83 SVEPYTKQQLNNMSFAEIIMGYKI 106

Coiled-coil domain of Signal Transducer and Activator of Transcription 4 (STAT4); This family consists of the coiled-coil (alpha) domain of the STAT4 proteins (Signal Transducer and Activator of Transcription 4, or Signal Transduction And Transcription 4). STAT4 expression is restricted to spermatozoa, myeloid cells, and T lymphocytes, making it distinct from other STATs. It acts as the major signaling transducing STATs in response to interleukin-12 (IL-12) by inducing interferon-gamma (IFNgamma), and is a central mediator in generating inflammation during protective immune responses and immune-mediated diseases. STAT4 is a critical regulator of Th1 differentiation and inflammatory disease. It is essential for the differentiation and function of many immune cells, including natural killer cells, dendritic cells, mast cells and T helper cells. STAT4-mediated signaling promotes the production of autoimmune-associated components, which are implicated in the pathogenesis of autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis and psoriasis, making STAT4 a promising therapeutic target for autoimmune diseases. Variations in STAT4 gene are linked to the development of systemic lupus erythematosus (SLE) in humans. STAT4 activation is detected in chronic liver diseases; polymorphism in STAT4 gene has been shown to be associated with the antiviral response in primary biliary cirrhosis (PBC), HCV-associated liver fibrosis, hepatocellular carcinoma (HCC), chronic hepatitis C and in drug-induced liver injury (DILI). STAT4 may inhibit HCC development by modulating HCC cell proliferation. Studies show that increased expression of STAT4 is positively correlated with the depth of invasion in colorectal cancer (CRC) patients, and the growth and invasion of CRC cells are repressed by inhibition of STAT4 expression, making STAT4 a promising therapeutic target for the treatment of CRC.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 141 QKELDSKVRNVKDKVMCIEHEIKSLEDLQDEYDFKCKTLQNRE-HETNgvaKSDQKQEQLLLKKMYLMLDNKRKEVVHKI 219
Cdd:cd16854     1 QRNVEHKVSAIKNSVQMTDQDTKYLEDLQDEFDFRYKTIQTMDqGDKN---SILMKQEVTTLQEMLNSLDFKRKEALSKM 77

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 220 IELLNVTELTQNALINDELVEWKRRQQSACIGGPPNACLDQLQNWFTIVAESLQQVRQQLKKLEELEQKYTYEHDPITKN 299
Cdd:cd16854    78 TQIINEIDLLMSSMLTEELKDWKRRQQIACIGGPLHGGLDQLQNWFTLLAESLFQLRRQLEKLDELSTKVTYEGDPIPLQ 157

                         170
                  ....*....|....*.
gi 1862755518 300 KQVLWDRTFSLFQQLI 315
Cdd:cd16854   158 RPQLLERVTFLIYNLF 173

Src homology 2 (SH2) domain found in signal transducer and activator of transcription (STAT) family; STAT proteins mediate the signaling of cytokines and a number of growth factors from the receptors of these extracellular signaling molecules to the cell nucleus. STATs are specifically phosphorylated by receptor-associated Janus kinases, receptor tyrosine kinases, or cytoplasmic tyrosine kinases. The phosphorylated STAT molecules dimerize by reciprocal binding of their SH2 domains to the phosphotyrosine residues. These dimeric STATs translocate into the nucleus, bind to specific DNA sequences, and regulate the transcription of their target genes. However there are a number of unphosphorylated STATs that travel between the cytoplasm and nucleus and some STATs that exist as dimers in unstimulated cells that can exert biological functions independent of being activated by a receptor. There are seven mammalian STAT family members which have been identified: STAT1, STAT2, STAT3, STAT4, STAT5 (STAT5A and STAT5B), and STAT6. There are 6 conserved domains in STAT: N-terminal domain (NTD), coiled-coil domain (CCD), DNA-binding domain (DBD), alpha-helical linker domain (LD), SH2 domain, and transactivation domain (TAD). NTD is involved in dimerization of unphosphorylated STATs monomers and for the tetramerization between STAT1, STAT3, STAT4 and STAT5 on promoters with two or more tandem STAT binding sites. It also plays a role in promoting interactions with transcriptional co-activators such as CREB binding protein (CBP)/p300, as well as being important for nuclear import and deactivation of STATs involving tyrosine de-phosphorylation. The CCD interacts with other proteins, such as IFN regulatory protein 9 (IRF-9/p48) with STAT1 and c-JUN with STAT3 and is also thought to participate in the negative regulation of these proteins. Distinct genes are bound to STATs via their DBD domain. This domain is also involved in nuclear translocation of activated STAT1 and STAT3 phosphorylated dimers upon cytokine stimulation. LD links the DNA-binding and SH2 domains and is important for the transcriptional activation of STAT1 in response to IFN-gamma. It also plays a role in protein-protein interactions and has also been implicated in the constitutive nucleocytoplasmic shuttling of unphosphorylated STATs in resting cells. The SH2 domain is necessary for receptor association and tyrosine phosphodimer formation. Residues within this domain may be particularly important for some cellular functions mediated by the STATs as well as residues adjacent to this domain. The TAD interacts with several proteins, namely minichromosome maintenance complex component 5 (MCM5), breast cancer 1 (BRCA1) and CBP/p300. TAD also contains a modulatory phosphorylation site that regulates STAT activity and is necessary for maximal transcription of a number of target genes. The conserved tyrosine residue present in the C-terminus is crucial for dimerization via interaction with the SH2 domain upon the interaction of the ligand with the receptor. STAT activation by tyrosine phosphorylation also determines nuclear import and retention, DNA binding to specific DNA elements in the promoters of responsive genes, and transcriptional activation of STAT dimers. In addition to the SH2 domain there is a coiled-coil domain, a DNA binding domain, and a transactivation domain in the STAT proteins. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 559 WIESILELIKKHLLPLWNDGCIMGFISKERERALLKDQQPGTFLLRFSESSrEGAITFTWVERSQNgGEPDFHAVEPYTK 638
Cdd:cd09919     1 WFFAIMLLTKRHLLKLWQDGLIMGFISKEEAEDLLKKKPPGTFLLRFSDSE-LGGITIAWVNEDPD-GQSQVIHLQPYTK 78

                          90
                  ....*....|....*.
gi 1862755518 639 KELSAVTFPDIIRNYK 654
Cdd:cd09919    79 KDLDIRSLADRIRDLP 94

Src homology 2 (SH2) domain found in signal transducer and activator of transcription (STAT) 2 proteins; STAT2 is a member of the STAT protein family. In response to interferon, STAT2 forms a complex with STAT1 and IFN regulatory factor family protein p48 (ISGF3G), in which this protein acts as a transactivator, but lacks the ability to bind DNA directly. Transcription adaptor P300/CBP (EP300/CREBBP) has been shown to interact specifically with STAT2, which is thought to be involved in the process of blocking IFN-alpha response by adenovirus. STAT2 has been shown to interact with MED14, CREB-binding protein, SMARCA4, STAT1, IFNAR2, IFNAR1, and ISGF3G. STAT proteins mediate the signaling of cytokines and a number of growth factors from the receptors of these extracellular signaling molecules to the cell nucleus. STATs are specifically phosphorylated by receptor-associated Janus kinases, receptor tyrosine kinases, or cytoplasmic tyrosine kinases. The phosphorylated STAT molecules dimerize by reciprocal binding of their SH2 domains to the phosphotyrosine residues. These dimeric STATs translocate into the nucleus, bind to specific DNA sequences, and regulate the transcription of their target genes. However there are a number of unphosphorylated STATs that travel between the cytoplasm and nucleus and some STATs that exist as dimers in unstimulated cells that can exert biological functions independent of being activated. There are seven mammalian STAT family members which have been identified: STAT1, STAT2, STAT3, STAT4, STAT5 (STAT5A and STAT5B), and STAT6. There are 6 conserved domains in STAT: N-terminal domain (NTD), coiled-coil domain (CCD), DNA-binding domain (DBD), alpha-helical linker domain (LD), SH2 domain, and transactivation domain (TAD). NTD is involved in dimerization of unphosphorylated STATs monomers and for the tetramerization between STAT1, STAT3, STAT4 and STAT5 on promoters with two or more tandem STAT binding sites. It also plays a role in promoting interactions with transcriptional co-activators such as CREB binding protein (CBP)/p300, as well as being important for nuclear import and deactivation of STATs involving tyrosine de-phosphorylation. CCD interacts with other proteins, such as IFN regulatory protein 9 (IRF-9/p48) with STAT1 and c-JUN with STAT3 and is also thought to participate in the negative regulation of these proteins. Distinct genes are bound to STATs via their DBD domain. This domain is also involved in nuclear translocation of activated STAT1 and STAT3 phosphorylated dimers upon cytokine stimulation. LD links the DNA-binding and SH2 domains and is important for the transcriptional activation of STAT1 in response to IFN-gamma. It also plays a role in protein-protein interactions and has also been implicated in the constitutive nucleocytoplasmic shuttling of unphosphorylated STATs in resting cells. The SH2 domain is necessary for receptor association and tyrosine phosphodimer formation. Residues within this domain may be particularly important for some cellular functions mediated by the STATs as well as residues adjacent to this domain. The TAD interacts with several proteins, namely minichromosome maintenance complex component 5 (MCM5), breast cancer 1 (BRCA1) and CBP/p300. TAD also contains a modulatory phosphorylation site that regulates STAT activity and is necessary for maximal transcription of a number of target genes. The conserved tyrosine residue present in the C-terminus is crucial for dimerization via interaction with the SH2 domain upon the interaction of the ligand with the receptor. STAT activation by tyrosine phosphorylation also determines nuclear import and retention, DNA binding to specific DNA elements in the promoters of responsive genes, and transcriptional activation of STAT dimers. In addition to the SH2 domain there is a coiled-coil domain, a DNA binding domain, and a transactivation domain in the STAT proteins. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 559 WIESILELIKKHLLPLWNDGCIMGFISKERERALLKDQQPGTFLLRFSESSrEGAITFTWVERsQNGGEPDFHAVEPYTK 638
Cdd:cd10373     1 WLDKILELVHDHLKDLWKDGRIMGFVSRNQERRLLKKTISGTFLLRFSETS-EGGITCSWVEH-QDDDKVLIYSVQPYTK 78

                          90
                  ....*....|....*..
gi 1862755518 639 KELSAVTFPDIIRNYKV 655
Cdd:cd10373    79 EVLQSLPLTEIIRHYQL 95

DNA-binding domain of Signal Transducer and Activator of Transcription 5 (STAT5); This family consists of the DNA-binding domain (DBD) of the STAT5 proteins (Signal Transducer and Activator of Transcription 5, or Signal Transduction And Transcription 4), which include STAT5A and STAT5B, both of which are >90% identical despite being encoded by separate genes. The DNA binding domain has an Ig-like fold. STAT5A and STAT5B regulate erythropoiesis, lymphopoiesis, and the maintenance of the hematopoietic stem cell population. STAT5A and STAT5B have overlapping and redundant functions; both isoforms can be activated by the same set of cytokines, but some cytokines preferentially activate either STAT5A or STAT5B, e.g. during pregnancy and lactation, STAT5A rather than STAT5B is required for the production of luminal progenitor cells from mammary stem cells and is essential for the differentiation of milk producing alveolar cells during pregnancy. STAT5 has been found to be constitutively phosphorylated in cancer cells, and therefore constantly activated, either by aberrant cell signaling expression or by mutations. It differentially regulates cellular behavior in human mammary carcinoma. Prolactin (PRL) in the prostate gland can induce growth and survival of prostate cancer cells and tissues through the activation of STAT5, its downstream target; PRL expression and STAT5 activation correlates with disease severity. STAT5A and STAT5B are central signaling molecules in leukemias driven by Abelson fusion tyrosine kinases, displaying unique nuclear shuttling mechanisms and having a key role in resistance of leukemic cells against treatment with tyrosine kinase inhibitors (TKI). In addition, STAT5A and STAT5B promote survival of leukemic stem cells. STAT5 is a key transcription factor for IL-3-mediated inhibition of RANKL-induced osteoclastogenesis via the induction of the expression of Id genes. Autosomal recessive STAT5B mutations are associated with severe growth failure, insulin-like growth factor (IGF) deficiency and growth hormone insensitivity (GHI) syndrome. STAT5B deficiency can lead to potentially fatal primary immunodeficiency.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 319 FVVERQPcmpthpqrPLVLKTGVQFTVKLRLLVKlQELNYNL-------------KVKVLFDKDVNERNTVKGfrkfNIL 385
Cdd:cd16849     1 FIIEKQP--------PQVLKTQTRFAATVRLLVG-GKLNVHMnppqvkatiiseqQAKALLKNENITRNETSG----EIL 67

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 386 gTHTKVMNMEESTnGSLAAEFRHLQLKEQKNAGTRTNEgplIVTEELHSLSFETQLCQPG--LVIDLETTSLPVVVISNV 463
Cdd:cd16849    68 -NNCGVMEYHQAT-GQLSVSFRNMSLKRIKRADKRGAE---SVTEEKFTILFQSQFSVGGneLVFQVWTLSLPVVVIVHG 142

                         170
                  ....*....|....
gi 1862755518 464 SQLPSGWASILWYN 477
Cdd:cd16849   143 NQESNATATVLWDN 156

Src homology 2 (SH2) domain found in signal transducer and activator of transcription (STAT) 5 proteins; STAT5 is a member of the STAT family of transcription factors. Two highly related proteins, STAT5a and STAT5b are encoded by separate genes, but are 90% identical at the amino acid level. Both STAT5a and STAT5b are ubiquitously expressed and functionally interchangeable. Mice lacking either STAT5a or STAT5b have mild defects in prolactin dependent mammary differentiation or sexually dimorphic growth hormone-dependent effects, respectively. Mice lacking both STAT5a and STAT5b exhibit a perinatal lethal phenotype and have multiple defects, including anemia and a virtual absence of B and T lymphocytes. STAT proteins mediate the signaling of cytokines and a number of growth factors from the receptors of these extracellular signaling molecules to the cell nucleus. STATs are specifically phosphorylated by receptor-associated Janus kinases, receptor tyrosine kinases, or cytoplasmic tyrosine kinases. The phosphorylated STAT molecules dimerize by reciprocal binding of their SH2 domains to the phosphotyrosine residues. These dimeric STATs translocate into the nucleus, bind to specific DNA sequences, and regulate the transcription of their target genes. However there are a number of unphosphorylated STATs that travel between the cytoplasm and nucleus and some STATs that exist as dimers in unstimulated cells that can exert biological functions independent of being activated. There are seven mammalian STAT family members which have been identified: STAT1, STAT2, STAT3, STAT4, STAT5 (STAT5A and STAT5B), and STAT6. There are 6 conserved domains in STAT: N-terminal domain (NTD), coiled-coil domain (CCD), DNA-binding domain (DBD), alpha-helical linker domain (LD), SH2 domain, and transactivation domain (TAD). NTD is involved in dimerization of unphosphorylated STATs monomers and for the tetramerization between STAT1, STAT3, STAT4 and STAT5 on promoters with two or more tandem STAT binding sites. It also plays a role in promoting interactions with transcriptional co-activators such as CREB binding protein (CBP)/p300, as well as being important for nuclear import and deactivation of STATs involving tyrosine de-phosphorylation. CCD interacts with other proteins, such as IFN regulatory protein 9 (IRF-9/p48) with STAT1 and c-JUN with STAT3 and is also thought to participate in the negative regulation of these proteins. Distinct genes are bound to STATs via their DBD domain. This domain is also involved in nuclear translocation of activated STAT1 and STAT3 phosphorylated dimers upon cytokine stimulation. LD links the DNA-binding and SH2 domains and is important for the transcriptional activation of STAT1 in response to IFN-gamma. It also plays a role in protein-protein interactions and has also been implicated in the constitutive nucleocytoplasmic shuttling of unphosphorylated STATs in resting cells. The SH2 domain is necessary for receptor association and tyrosine phosphodimer formation. Residues within this domain may be particularly important for some cellular functions mediated by the STATs as well as residues adjacent to this domain. The TAD interacts with several proteins, namely minichromosome maintenance complex component 5 (MCM5), breast cancer 1 (BRCA1) and CBP/p300. TAD also contains a modulatory phosphorylation site that regulates STAT activity and is necessary for maximal transcription of a number of target genes. The conserved tyrosine residue present in the C-terminus is crucial for dimerization via interaction with the SH2 domain upon the interaction of the ligand with the receptor. STAT activation by tyrosine phosphorylation also determines nuclear import and retention, DNA binding to specific DNA elements in the promoters of responsive genes, and transcriptional activation of STAT dimers. In addition to the SH2 domain there is a coiled-coil domain, a DNA binding domain, and a transactivation domain in the STAT proteins.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 559 WIESILELIKKHLLPLWNDGCIMGFISKERERALLKDQQPGTFLLRFSESSReGAITFTWVERSQnggEPDFHAVEPYTK 638
Cdd:cd10376     1 WFDGVMEVLKKHLKPHWNDGAILGFVNKQQAHDLLINKPDGTFLLRFSDSEI-GGITIAWKFDSP---DRALWNLMPFTT 76

                          90
                  ....*....|
gi 1862755518 639 KELSAVTFPD 648
Cdd:cd10376    77 RDFSIRSLAD 86

Coiled-coil domain of Signal Transducer and Activator of Transcription 5 (STAT5); This family consists of the coiled-coil (alpha) domain of the STAT5 proteins (Signal Transducer and Activator of Transcription 5, or Signal Transduction And Transcription 5) which include STAT5A and STAT5B, both of which are >90% identical despite being encoded by separate genes. The coiled-coil domain (CCD) of STAT5A and STAT5B appears to be required for constitutive nuclear localization signals (NLS) function; small deletions within the CCD can abrogate nuclear import. Studies show that the CCD binds to the importin-alpha3 NLS adapter in most cells. STAT5A and STAT5B regulate erythropoiesis, lymphopoiesis, and the maintenance of the hematopoietic stem cell population. STAT5A and STAT5B have overlapping and redundant functions; both isoforms can be activated by the same set of cytokines, but some cytokines preferentially activate either STAT5A or STAT5B, e.g. during pregnancy and lactation, STAT5A rather than STAT5B is required for the production of luminal progenitor cells from mammary stem cells and is essential for the differentiation of milk producing alveolar cells during pregnancy. STAT5 has been found to be constitutively phosphorylated in cancer cells, and therefore constantly activated, either by aberrant cell signaling expression or by mutations. It differentially regulates cellular behavior in human mammary carcinoma. Prolactin (PRL) in the prostate gland can induce growth and survival of prostate cancer cells and tissues through the activation of STAT5, its downstream target; PRL expression and STAT5 activation correlates with disease severity. STAT5A and STAT5B are central signaling molecules in leukemias driven by Abelson fusion tyrosine kinases, displaying unique nuclear shuttling mechanisms and having a key role in resistance of leukemic cells against treatment with tyrosine kinase inhibitors (TKI). In addition, STAT5A and STAT5B promote survival of leukemic stem cells. STAT5 is a key transcription factor for IL-3-mediated inhibition of RANKL-induced osteoclastogenesis via the induction of the expression of Id genes. Autosomal recessive STAT5B mutations are associated with severe growth failure, insulin-like growth factor (IGF) deficiency and growth hormone insensitivity (GHI) syndrome. STAT5B deficiency can lead to potentially fatal primary immunodeficiency.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 210 NKRKEVVHKIIELLNVTELTQNALINDELVEWKRRQQSACIGGPPNACLDQLQNWFTIVAESLQQVRQQLKKLEELEQKY 289
Cdd:cd16855    86 QLRMELADKFKKTIQLLSKLQSRVLDEELIQWKRQQQLAGNGAPFESNLDTIQEWCESLAEIIWQNRQQIKRAERLKQKL 165

                          90
                  ....*....|
gi 1862755518 290 TYEHDPITKN 299
Cdd:cd16855   166 PIPLPPEQKD 175

DNA-binding domain of Signal Transducer and Activator of Transcription 6 (STAT6); This family consists of the DNA-binding domain (DBD) of the STAT6 proteins (Signal Transducer and Activator of Transcription 6, or Signal Transduction And Transcription 6). The DNA binding domain has an Ig-like fold. STAT6 is essential for the functional responses of T helper 2 (Th2) lymphocyte mediated by interleukins IL-4 and IL-13. STAT6 almost exclusively mediates the expression of genes activated by these cytokines; IL-4 signaling regulates the expression of genes involved in immune and anti-inflammatory responses. Abnormal production of IL-4 and IL-13 play important roles in the pathogenesis of asthma where upregulation of the Th2 response mediated by IL-4/IL-13 is a main characteristic. STAT6 has a unique extended transactivation domain, not found in other STATs, through which it recruits p300/CBP and NCoA-1, two coactivators needed for transcriptional activation by IL-4. STAT6 activation is linked to Kaposi's sarcoma-associated herpesvirus (KSHV)-associated cancers such as primary effusion lymphoma, a cancerous proliferation of B cells. Studies show that Meningeal solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) represent a histopathologic spectrum linked by STAT6 nuclear expression and recurrent somatic fusions of the two genes, NGFI-A-binding protein 2 (NAB2) and STAT6 (NAB2-STAT6), similar to their soft tissue counterparts. It is associated with local recurrence and late distance metastasis of brain tumors to extracranial sites.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 319 FVVERQPcmpthpqrPLVLKTGVQFTVKLRLLVKLQELNYNLKVKVLFDKDVNERNTvkgfRKFNILG------------ 386
Cdd:cd16850     1 FLVEKQP--------PQVLKTQTKFQAGVRFLLGLRFLGAPAKPPLVRADMVTEKQA----RELSQPQgpgagnentgei 68

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1862755518 387 THTKVMNMEESTNGSLAAEFRHLQLKEQKNAGTRTNEGpliVTEELHSLSFETQLC-QPG-LVIDLETTSLPVVVISNVS 464
Cdd:cd16850    69 INNTVPLENNITSKCCCATFKNLLLKKIKRCERKGSES---VTEEKCAVLFSADFTlGPGkLPIQLQALSLPVVVIVHGN 145

                         170
                  ....*....|...
gi 1862755518 465 QLPSGWASILWYN 477
Cdd:cd16850   146 QDNNAKATILWDN 158

Src homology 2 (SH2) domain; In general, SH2 domains are involved in signal transduction; they bind pTyr-containing polypeptide ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites. They are present in a wide array of proteins including: adaptor proteins (Nck1, Crk, Grb2), scaffolds (Slp76, Shc, Dapp1), kinases (Src, Syk, Fps, Tec), phosphatases (Shp-1, Shp-2), transcription factors (STAT1), Ras signaling molecules (Ras-Gap), ubiquitination factors (c-Cbl), cytoskeleton regulators (Tensin), signal regulators (SAP), and phospholipid second messengers (PLCgamma), amongst others.

                          10        20
                  ....*....|....*....|....*....
gi 1862755518 582 GFISKERERALLKDQQPGTFLLRFSESSR 610
Cdd:cd00173     5 GSISREEAERLLRGKPDGTFLVRESSSEP 33

Src homology 2 domains; Src homology 2 domains bind phosphotyrosine-containing polypeptides via 2 surface pockets. Specificity is provided via interaction with residues that are distinct from the phosphotyrosine. Only a single occurrence of a SH2 domain has been found in S. cerevisiae.

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*
gi 1862755518  581 MGFISKERERALLKDQQPGTFLLRFSESSREG-AITFTWVERSQN 624
Cdd:smart00252   5 HGFISREEAEKLLKNEGDGDFLVRDSESSPGDyVLSVRVKGKVKH 49

Src homology 2 (SH2) domain found in SH2 adaptor proteins A (SHA) Signal transducers; Signal transducing adaptor proteins are accessory to main proteins in a signal transduction pathway. These proteins lack intrinsic enzymatic activity, but mediate specific protein-protein interactions that drive the formation of protein complexes. Adaptor proteins usually contain several domains within their structure (e.g. SH2 and SH3 domains) which allow specific interactions with several other specific proteins. Not much is known about the SHA protein except that it is predicted to act as a transcription factor. Arabidopsis SHA pulled down a 120-kD tyrosine-phosphorylated protein in vitro. In addition to the SH2 domain there is a coiled-coil domain, a DNA binding domain, and a transactivation domain in the STAT proteins. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 1862755518 573 PLWndgcIMGFISKERERALLKDQQPGTFLLRFSES 608
Cdd:cd10338    10 PKW----IEGFITKEEAERSLQGQVPGTFILRFPTS 41