View source for 3i6u


==Structure and Activation Mechanism of the CHK2 DNA-Damage Checkpoint Kinase==
<StructureSection load='3i6u' size='340' side='right'caption='[[3i6u]], [[Resolution|resolution]] 3.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3i6u]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3I6U OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3I6U FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3i6u FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3i6u OCA], [https://pdbe.org/3i6u PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3i6u RCSB], [https://www.ebi.ac.uk/pdbsum/3i6u PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3i6u ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/CHK2_HUMAN CHK2_HUMAN] Defects in CHEK2 are associated with Li-Fraumeni syndrome 2 (LFS2) [MIM:[https://omim.org/entry/609265 609265]; a highly penetrant familial cancer phenotype usually associated with inherited mutations in p53/TP53.<ref>PMID:11719428</ref>   Defects in CHEK2 may be a cause of susceptibility to prostate cancer (PC) [MIM:[https://omim.org/entry/176807 176807]. It is a malignancy originating in tissues of the prostate. Most prostate cancers are adenocarcinomas that develop in the acini of the prostatic ducts. Other rare histopathologic types of prostate cancer that occur in approximately 5% of patients include small cell carcinoma, mucinous carcinoma, prostatic ductal carcinoma, transitional cell carcinoma, squamous cell carcinoma, basal cell carcinoma, adenoid cystic carcinoma (basaloid), signet-ring cell carcinoma and neuroendocrine carcinoma.  Defects in CHEK2 are found in some patients with osteogenic sarcoma (OSRC) [MIM:[https://omim.org/entry/259500 259500].  Defects in CHEK2 is a cause of susceptibility to breast cancer (BC) [MIM:[https://omim.org/entry/114480 114480]. A common malignancy originating from breast epithelial tissue. Breast neoplasms can be distinguished by their histologic pattern. Invasive ductal carcinoma is by far the most common type. Breast cancer is etiologically and genetically heterogeneous. Important genetic factors have been indicated by familial occurrence and bilateral involvement. Mutations at more than one locus can be involved in different families or even in the same case. Note=CHEK2 variants are associated with susceptibility to breast cancer and contribute to a substantial fraction of familial breast cancer (PubMed:12094328).<ref>PMID:12094328</ref> <ref>PMID:21618645</ref> 
== Function ==
[https://www.uniprot.org/uniprot/CHK2_HUMAN CHK2_HUMAN] Serine/threonine-protein kinase which is required for checkpoint-mediated cell cycle arrest, activation of DNA repair and apoptosis in response to the presence of DNA double-strand breaks. May also negatively regulate cell cycle progression during unperturbed cell cycles. Following activation, phosphorylates numerous effectors preferentially at the consensus sequence [L-X-R-X-X-S/T]. Regulates cell cycle checkpoint arrest through phosphorylation of CDC25A, CDC25B and CDC25C, inhibiting their activity. Inhibition of CDC25 phosphatase activity leads to increased inhibitory tyrosine phosphorylation of CDK-cyclin complexes and blocks cell cycle progression. May also phosphorylate NEK6 which is involved in G2/M cell cycle arrest. Regulates DNA repair through phosphorylation of BRCA2, enhancing the association of RAD51 with chromatin which promotes DNA repair by homologous recombination. Also stimulates the transcription of genes involved in DNA repair (including BRCA2) through the phosphorylation and activation of the transcription factor FOXM1. Regulates apoptosis through the phosphorylation of p53/TP53, MDM4 and PML. Phosphorylation of p53/TP53 at 'Ser-20' by CHEK2 may alleviate inhibition by MDM2, leading to accumulation of active p53/TP53. Phosphorylation of MDM4 may also reduce degradation of p53/TP53. Also controls the transcription of pro-apoptotic genes through phosphorylation of the transcription factor E2F1. Tumor suppressor, it may also have a DNA damage-independent function in mitotic spindle assembly by phosphorylating BRCA1. Its absence may be a cause of the chromosomal instability observed in some cancer cells.<ref>PMID:9836640</ref> <ref>PMID:9889122</ref> <ref>PMID:10097108</ref> <ref>PMID:10724175</ref> <ref>PMID:11298456</ref> <ref>PMID:12402044</ref> <ref>PMID:12810724</ref> <ref>PMID:12717439</ref> <ref>PMID:12607004</ref> <ref>PMID:16163388</ref> <ref>PMID:17380128</ref> <ref>PMID:17715138</ref> <ref>PMID:17101782</ref> <ref>PMID:18728393</ref> <ref>PMID:18644861</ref> <ref>PMID:18317453</ref> <ref>PMID:20364141</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/i6/3i6u_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/main_output.php?pdb_ID=3i6u ConSurf].
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== Publication Abstract from PubMed ==
The CHK2 protein kinase is an important transducer of DNA damage checkpoint signals, and its mutation contributes to hereditary and sporadic cancer. CHK2 activation is triggered by the phosphorylation of Thr68 by the DNA damage-activated ATM kinase. This leads to transient CHK2 dimerization, in part through intermolecular phosphoThr68-FHA domain interactions. Dimerization promotes kinase activation through activation-loop autophosphorylation, but the mechanism of this process has not been clear. The dimeric crystal structure of CHK2, described here, in conjunction with biochemical and mutational data reveals that productive CHK2 dimerization additionally involves intermolecular FHA-kinase domain and FHA-FHA interactions. Ile157, mutated in the Li-Fraumeni cancer-predisposition syndrome, plays a central role in the FHA-kinase domain interface, explaining the lack of dimerization and autophosphorylation of this mutant. In the dimer, the kinase active sites face each other in close proximity, indicating that dimerization may also serve to optimally position the kinase active sites for efficient activation loop transphosphorylation.

Structure and activation mechanism of the CHK2 DNA damage checkpoint kinase.,Cai Z, Chehab NH, Pavletich NP Mol Cell. 2009 Sep 24;35(6):818-29. PMID:19782031<ref>PMID:19782031</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 3i6u" style="background-color:#fffaf0;"></div>

==See Also==
*[[Serine/threonine protein kinase 3D structures|Serine/threonine protein kinase 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Pavletich NP]]