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{{STRUCTURE_1dd1| PDB=1dd1  | SCENE=  }}
==CRYSTAL STRUCTURE ANALYSIS OF THE SMAD4 ACTIVE FRAGMENT==
===CRYSTAL STRUCTURE ANALYSIS OF THE SMAD4 ACTIVE FRAGMENT===
<StructureSection load='1dd1' size='340' side='right' caption='[[1dd1]], [[Resolution|resolution]] 2.62&Aring;' scene=''>
{{ABSTRACT_PUBMED_10647180}}
== Structural highlights ==
<table><tr><td colspan='2'>[[1dd1]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DD1 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1DD1 FirstGlance]. <br>
</td></tr><tr><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene><br>
<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1dd1 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1dd1 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1dd1 RCSB], [http://www.ebi.ac.uk/pdbsum/1dd1 PDBsum]</span></td></tr>
<table>
== Disease ==
[[http://www.uniprot.org/uniprot/SMAD4_HUMAN SMAD4_HUMAN]] Defects in SMAD4 are a cause of pancreatic cancer (PNCA) [MIM:[http://omim.org/entry/260350 260350]]. Defects in SMAD4 are a cause of juvenile polyposis syndrome (JPS) [MIM:[http://omim.org/entry/174900 174900]]; also known as juvenile intestinal polyposis (JIP). JPS is an autosomal dominant gastrointestinal hamartomatous polyposis syndrome in which patients are at risk for developing gastrointestinal cancers. The lesions are typified by a smooth histological appearance, predominant stroma, cystic spaces and lack of a smooth muscle core. Multiple juvenile polyps usually occur in a number of Mendelian disorders. Sometimes, these polyps occur without associated features as in JPS; here, polyps tend to occur in the large bowel and are associated with an increased risk of colon and other gastrointestinal cancers.<ref>PMID:9811934</ref> <ref>PMID:12417513</ref>  Defects in SMAD4 are a cause of juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome (JP/HHT) [MIM:[http://omim.org/entry/175050 175050]]. JP/HHT syndrome phenotype consists of the coexistence of juvenile polyposis (JIP) and hereditary hemorrhagic telangiectasia (HHT) [MIM:[http://omim.org/entry/187300 187300]] in a single individual. JIP and HHT are autosomal dominant disorders with distinct and non-overlapping clinical features. The former, an inherited gastrointestinal malignancy predisposition, is caused by mutations in SMAD4 or BMPR1A, and the latter is a vascular malformation disorder caused by mutations in ENG or ACVRL1. All four genes encode proteins involved in the transforming-growth-factor-signaling pathway. Although there are reports of patients and families with phenotypes of both disorders combined, the genetic etiology of this association is unknown.  Defects in SMAD4 may be a cause of colorectal cancer (CRC) [MIM:[http://omim.org/entry/114500 114500]].  Defects in SMAD4 may be a cause of primary pulmonary hypertension (PPH1) [MIM:[http://omim.org/entry/178600 178600]]. A rare disorder characterized by plexiform lesions of proliferating endothelial cells in pulmonary arterioles. The lesions lead to elevated pulmonary arterial pression, right ventricular failure, and death. The disease can occur from infancy throughout life and it has a mean age at onset of 36 years. Penetrance is reduced. Although familial PPH1 is rare, cases secondary to known etiologies are more common and include those associated with the appetite-suppressant drugs.<ref>PMID:21898662</ref>  Defects in SMAD4 are the cause of Myhre syndrome (MYHRS) [MIM:[http://omim.org/entry/139210 139210]]. MYHRS is a syndrome characterized by pre- and postnatal growth deficiency, mental retardation, generalized muscle hypertrophy and striking muscular build, decreased joint mobility, cryptorchidism, and unusual facies. Dysmorphic facial features include microcephaly, midface hypoplasia, prognathism, and blepharophimosis. Typical skeletal anomalies are short stature, square body shape, broad ribs, iliac hypoplasia, brachydactyly, flattened vertebrae, and thickened calvaria. Other features, such as congenital heart disease, may also occur.<ref>PMID:22243968</ref> <ref>PMID:22158539</ref>  
== Function ==
[[http://www.uniprot.org/uniprot/SMAD4_HUMAN SMAD4_HUMAN]] Common SMAD (co-SMAD) is the coactivator and mediator of signal transduction by TGF-beta (transforming growth factor). Component of the heterotrimeric SMAD2/SMAD3-SMAD4 complex that forms in the nucleus and is required for the TGF-mediated signaling. Promotes binding of the SMAD2/SMAD4/FAST-1 complex to DNA and provides an activation function required for SMAD1 or SMAD2 to stimulate transcription. Component of the multimeric SMAD3/SMAD4/JUN/FOS complex which forms at the AP1 promoter site; required for syngernistic transcriptional activity in response to TGF-beta. May act as a tumor suppressor. Positively regulates PDPK1 kinase activity by stimulating its dissociation from the 14-3-3 protein YWHAQ which acts as a negative regulator.<ref>PMID:9389648</ref> <ref>PMID:17327236</ref>  
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/dd/1dd1_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/chain_selection.php?pdb_ID=2ata ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
BACKGROUND: Smad4 functions as a common mediator of transforming growth factor beta (TGF-beta) signaling by forming complexes with the phosphorylated state of pathway-restricted SMAD proteins that act in specific signaling pathways to activate transcription. SMAD proteins comprise two domains, the MH1 and MH2 domain, separated by a linker region. The transcriptional activity and synergistic effect of Smad4 require a stretch of proline-rich sequence, the SMAD-activation domain (SAD), located N-terminal of the MH2 domain. To understand how the SAD contributes to Smad4 function, the crystal structure of a fragment including the SAD and MH2 domain (S4AF) was determined. RESULTS: The structure of the S4AF trimer reveals novel features important for Smad4 function. A Smad4-specific sequence insertion within the MH2 domain interacts with the C-terminal tail to form a structural extension from the core. This extension (the TOWER) contains a solvent-accessible glutamine-rich helix. The SAD reinforces the TOWER and the structural core through interactions; two residues involved in these interactions are targets of tumorigenic mutation. The solvent-accessible proline residues of the SAD are located on the same face as the glutamine-rich helix of the TOWER, forming a potential transcription activation surface. A tandem sulfate-ion-binding site was identified within the subunit interface, which may interact with the phosphorylated C-terminal sequence of pathway-restricted SMAD proteins. CONCLUSIONS: The structure suggests that the SAD provides transcriptional capability by reinforcing the structural core and coordinating with the TOWER to present the proline-rich and glutamine-rich surfaces for interaction with transcription partners. The sulfate-ion-binding sites are potential 'receptors' for the phosphorylated sequence of pathway-restricted SMAD proteins in forming a heteromeric complex. The structure thus provides a new model that can be tested using biochemical and cellular approaches.


==Disease==
Crystal structure of a transcriptionally active Smad4 fragment.,Qin B, Lam SS, Lin K Structure. 1999 Dec 15;7(12):1493-503. PMID:10647180<ref>PMID:10647180</ref>
[[http://www.uniprot.org/uniprot/SMAD4_HUMAN SMAD4_HUMAN]] Defects in SMAD4 are a cause of pancreatic cancer (PNCA) [MIM:[http://omim.org/entry/260350 260350]].  Defects in SMAD4 are a cause of juvenile polyposis syndrome (JPS) [MIM:[http://omim.org/entry/174900 174900]]; also known as juvenile intestinal polyposis (JIP). JPS is an autosomal dominant gastrointestinal hamartomatous polyposis syndrome in which patients are at risk for developing gastrointestinal cancers. The lesions are typified by a smooth histological appearance, predominant stroma, cystic spaces and lack of a smooth muscle core. Multiple juvenile polyps usually occur in a number of Mendelian disorders. Sometimes, these polyps occur without associated features as in JPS; here, polyps tend to occur in the large bowel and are associated with an increased risk of colon and other gastrointestinal cancers.<ref>PMID:9811934</ref><ref>PMID:12417513</ref>  Defects in SMAD4 are a cause of juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome (JP/HHT) [MIM:[http://omim.org/entry/175050 175050]]. JP/HHT syndrome phenotype consists of the coexistence of juvenile polyposis (JIP) and hereditary hemorrhagic telangiectasia (HHT) [MIM:[http://omim.org/entry/187300 187300]] in a single individual. JIP and HHT are autosomal dominant disorders with distinct and non-overlapping clinical features. The former, an inherited gastrointestinal malignancy predisposition, is caused by mutations in SMAD4 or BMPR1A, and the latter is a vascular malformation disorder caused by mutations in ENG or ACVRL1. All four genes encode proteins involved in the transforming-growth-factor-signaling pathway. Although there are reports of patients and families with phenotypes of both disorders combined, the genetic etiology of this association is unknown.  Defects in SMAD4 may be a cause of colorectal cancer (CRC) [MIM:[http://omim.org/entry/114500 114500]].  Defects in SMAD4 may be a cause of primary pulmonary hypertension (PPH1) [MIM:[http://omim.org/entry/178600 178600]]. A rare disorder characterized by plexiform lesions of proliferating endothelial cells in pulmonary arterioles. The lesions lead to elevated pulmonary arterial pression, right ventricular failure, and death. The disease can occur from infancy throughout life and it has a mean age at onset of 36 years. Penetrance is reduced. Although familial PPH1 is rare, cases secondary to known etiologies are more common and include those associated with the appetite-suppressant drugs.<ref>PMID:21898662</ref>  Defects in SMAD4 are the cause of Myhre syndrome (MYHRS) [MIM:[http://omim.org/entry/139210 139210]]. MYHRS is a syndrome characterized by pre- and postnatal growth deficiency, mental retardation, generalized muscle hypertrophy and striking muscular build, decreased joint mobility, cryptorchidism, and unusual facies. Dysmorphic facial features include microcephaly, midface hypoplasia, prognathism, and blepharophimosis. Typical skeletal anomalies are short stature, square body shape, broad ribs, iliac hypoplasia, brachydactyly, flattened vertebrae, and thickened calvaria. Other features, such as congenital heart disease, may also occur.<ref>PMID:22243968</ref><ref>PMID:22158539</ref>  


==Function==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
[[http://www.uniprot.org/uniprot/SMAD4_HUMAN SMAD4_HUMAN]] Common SMAD (co-SMAD) is the coactivator and mediator of signal transduction by TGF-beta (transforming growth factor). Component of the heterotrimeric SMAD2/SMAD3-SMAD4 complex that forms in the nucleus and is required for the TGF-mediated signaling. Promotes binding of the SMAD2/SMAD4/FAST-1 complex to DNA and provides an activation function required for SMAD1 or SMAD2 to stimulate transcription. Component of the multimeric SMAD3/SMAD4/JUN/FOS complex which forms at the AP1 promoter site; required for syngernistic transcriptional activity in response to TGF-beta. May act as a tumor suppressor. Positively regulates PDPK1 kinase activity by stimulating its dissociation from the 14-3-3 protein YWHAQ which acts as a negative regulator.<ref>PMID:9389648</ref><ref>PMID:17327236</ref>  
</div>
 
== References ==
==About this Structure==
<references/>
[[1dd1]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DD1 OCA].
__TOC__
 
</StructureSection>
==Reference==
<ref group="xtra">PMID:010647180</ref><references group="xtra"/><references/>
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
[[Category: Lam, S W.]]
[[Category: Lam, S W.]]

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