2x8d is a 1 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
CHK1_HUMAN Serine/threonine-protein kinase which is required for checkpoint-mediated cell cycle arrest and activation of DNA repair in response to the presence of DNA damage or unreplicated DNA. May also negatively regulate cell cycle progression during unperturbed cell cycles. This regulation is achieved by a number of mechanisms that together help to preserve the integrity of the genome. Recognizes the substrate consensus sequence [R-X-X-S/T]. Binds to and phosphorylates CDC25A, CDC25B and CDC25C. Phosphorylation of CDC25A at 'Ser-178' and 'Thr-507' and phosphorylation of CDC25C at 'Ser-216' creates binding sites for 14-3-3 proteins which inhibit CDC25A and CDC25C. Phosphorylation of CDC25A at 'Ser-76', 'Ser-124', 'Ser-178', 'Ser-279' and 'Ser-293' promotes proteolysis of CDC25A. Phosphorylation of CDC25A at 'Ser-76' primes the protein for subsequent phosphorylation at 'Ser-79', 'Ser-82' and 'Ser-88' by NEK11, which is required for polyubiquitination and degradation of CDCD25A. Inhibition of CDC25 leads to increased inhibitory tyrosine phosphorylation of CDK-cyclin complexes and blocks cell cycle progression. Also phosphorylates NEK6. Binds to and phosphorylates RAD51 at 'Thr-309', which promotes the release of RAD51 from BRCA2 and enhances the association of RAD51 with chromatin, thereby promoting DNA repair by homologous recombination. Phosphorylates multiple sites within the C-terminus of TP53, which promotes activation of TP53 by acetylation and promotes cell cycle arrest and suppression of cellular proliferation. Also promotes repair of DNA cross-links through phosphorylation of FANCE. Binds to and phosphorylates TLK1 at 'Ser-743', which prevents the TLK1-dependent phosphorylation of the chromatin assembly factor ASF1A. This may enhance chromatin assembly both in the presence or absence of DNA damage. May also play a role in replication fork maintenance through regulation of PCNA. May regulate the transcription of genes that regulate cell-cycle progression through the phosphorylation of histones. Phosphorylates histone H3.1 (to form H3T11ph), which leads to epigenetic inhibition of a subset of genes. May also phosphorylate RB1 to promote its interaction with the E2F family of transcription factors and subsequent cell cycle arrest.[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Isoform 2: Endogenous repressor of isoform 1, interacts with, and antagonizes CHK1 to promote the S to G2/M phase transition.[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Checkpoint Kinase-1 (Chk1, CHK1, CHEK1) is a Ser/Thr protein kinase that mediates cellular responses to DNA-damage. A novel class of Chk1 inhibitors, triazoloquinolones/triazolones (TZ's) was identified by high throughput screening. The optimization of these hits to provide a lead series is described.
Discovery of a novel class of triazolones as Checkpoint Kinase inhibitors--hit to lead exploration.,Oza V, Ashwell S, Brassil P, Breed J, Deng C, Ezhuthachan J, Haye H, Horn C, Janetka J, Lyne P, Newcombe N, Otterbien L, Pass M, Read J, Roswell S, Su M, Toader D, Yu D, Yu Y, Valentine A, Webborn P, White A, Zabludoff S, Zheng X Bioorg Med Chem Lett. 2010 Sep 1;20(17):5133-8. Epub 2010 Jul 29. PMID:20673630[53]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑Sanchez Y, Wong C, Thoma RS, Richman R, Wu Z, Piwnica-Worms H, Elledge SJ. Conservation of the Chk1 checkpoint pathway in mammals: linkage of DNA damage to Cdk regulation through Cdc25. Science. 1997 Sep 5;277(5331):1497-501. PMID:9278511
↑Shieh SY, Ahn J, Tamai K, Taya Y, Prives C. The human homologs of checkpoint kinases Chk1 and Cds1 (Chk2) phosphorylate p53 at multiple DNA damage-inducible sites. Genes Dev. 2000 Feb 1;14(3):289-300. PMID:10673501
↑Feijoo C, Hall-Jackson C, Wu R, Jenkins D, Leitch J, Gilbert DM, Smythe C. Activation of mammalian Chk1 during DNA replication arrest: a role for Chk1 in the intra-S phase checkpoint monitoring replication origin firing. J Cell Biol. 2001 Sep 3;154(5):913-23. PMID:11535615 doi:10.1083/jcb.200104099
↑Heffernan TP, Simpson DA, Frank AR, Heinloth AN, Paules RS, Cordeiro-Stone M, Kaufmann WK. An ATR- and Chk1-dependent S checkpoint inhibits replicon initiation following UVC-induced DNA damage. Mol Cell Biol. 2002 Dec;22(24):8552-61. PMID:12446774
↑Zhao H, Watkins JL, Piwnica-Worms H. Disruption of the checkpoint kinase 1/cell division cycle 25A pathway abrogates ionizing radiation-induced S and G2 checkpoints. Proc Natl Acad Sci U S A. 2002 Nov 12;99(23):14795-800. Epub 2002 Oct 24. PMID:12399544 doi:10.1073/pnas.182557299
↑Sorensen CS, Syljuasen RG, Falck J, Schroeder T, Ronnstrand L, Khanna KK, Zhou BB, Bartek J, Lukas J. Chk1 regulates the S phase checkpoint by coupling the physiological turnover and ionizing radiation-induced accelerated proteolysis of Cdc25A. Cancer Cell. 2003 Mar;3(3):247-58. PMID:12676583
↑Groth A, Lukas J, Nigg EA, Sillje HH, Wernstedt C, Bartek J, Hansen K. Human Tousled like kinases are targeted by an ATM- and Chk1-dependent DNA damage checkpoint. EMBO J. 2003 Apr 1;22(7):1676-87. PMID:12660173 doi:10.1093/emboj/cdg151
↑Jin J, Shirogane T, Xu L, Nalepa G, Qin J, Elledge SJ, Harper JW. SCFbeta-TRCP links Chk1 signaling to degradation of the Cdc25A protein phosphatase. Genes Dev. 2003 Dec 15;17(24):3062-74. Epub 2003 Dec 17. PMID:14681206 doi:10.1101/gad.1157503
↑Xiao Z, Chen Z, Gunasekera AH, Sowin TJ, Rosenberg SH, Fesik S, Zhang H. Chk1 mediates S and G2 arrests through Cdc25A degradation in response to DNA-damaging agents. J Biol Chem. 2003 Jun 13;278(24):21767-73. Epub 2003 Apr 3. PMID:12676925 doi:10.1074/jbc.M300229200
↑Hassepass I, Voit R, Hoffmann I. Phosphorylation at serine 75 is required for UV-mediated degradation of human Cdc25A phosphatase at the S-phase checkpoint. J Biol Chem. 2003 Aug 8;278(32):29824-9. Epub 2003 May 20. PMID:12759351 doi:10.1074/jbc.M302704200
↑Chen MS, Ryan CE, Piwnica-Worms H. Chk1 kinase negatively regulates mitotic function of Cdc25A phosphatase through 14-3-3 binding. Mol Cell Biol. 2003 Nov;23(21):7488-97. PMID:14559997
↑Pichierri P, Rosselli F. The DNA crosslink-induced S-phase checkpoint depends on ATR-CHK1 and ATR-NBS1-FANCD2 pathways. EMBO J. 2004 Mar 10;23(5):1178-87. Epub 2004 Feb 26. PMID:14988723 doi:10.1038/sj.emboj.7600113
↑Kramer A, Mailand N, Lukas C, Syljuasen RG, Wilkinson CJ, Nigg EA, Bartek J, Lukas J. Centrosome-associated Chk1 prevents premature activation of cyclin-B-Cdk1 kinase. Nat Cell Biol. 2004 Sep;6(9):884-91. Epub 2004 Aug 15. PMID:15311285 doi:10.1038/ncb1165
↑Ou YH, Chung PH, Sun TP, Shieh SY. p53 C-terminal phosphorylation by CHK1 and CHK2 participates in the regulation of DNA-damage-induced C-terminal acetylation. Mol Biol Cell. 2005 Apr;16(4):1684-95. Epub 2005 Jan 19. PMID:15659650 doi:E04-08-0689
↑Sorensen CS, Hansen LT, Dziegielewski J, Syljuasen RG, Lundin C, Bartek J, Helleday T. The cell-cycle checkpoint kinase Chk1 is required for mammalian homologous recombination repair. Nat Cell Biol. 2005 Feb;7(2):195-201. Epub 2005 Jan 23. PMID:15665856 doi:10.1038/ncb1212
↑Huang X, Tran T, Zhang L, Hatcher R, Zhang P. DNA damage-induced mitotic catastrophe is mediated by the Chk1-dependent mitotic exit DNA damage checkpoint. Proc Natl Acad Sci U S A. 2005 Jan 25;102(4):1065-70. Epub 2005 Jan 13. PMID:15650047 doi:10.1073/pnas.0409130102
↑Jin Y, Dai MS, Lu SZ, Xu Y, Luo Z, Zhao Y, Lu H. 14-3-3gamma binds to MDMX that is phosphorylated by UV-activated Chk1, resulting in p53 activation. EMBO J. 2006 Mar 22;25(6):1207-18. Epub 2006 Mar 2. PMID:16511572 doi:10.1038/sj.emboj.7601010
↑Chini CC, Chen J. Repeated phosphopeptide motifs in human Claspin are phosphorylated by Chk1 and mediate Claspin function. J Biol Chem. 2006 Nov 3;281(44):33276-82. Epub 2006 Sep 8. PMID:16963448 doi:10.1074/jbc.M604373200
↑Inoue Y, Kitagawa M, Taya Y. Phosphorylation of pRB at Ser612 by Chk1/2 leads to a complex between pRB and E2F-1 after DNA damage. EMBO J. 2007 Apr 18;26(8):2083-93. Epub 2007 Mar 22. PMID:17380128 doi:10.1038/sj.emboj.7601652
↑Wang X, Kennedy RD, Ray K, Stuckert P, Ellenberger T, D'Andrea AD. Chk1-mediated phosphorylation of FANCE is required for the Fanconi anemia/BRCA pathway. Mol Cell Biol. 2007 Apr;27(8):3098-108. Epub 2007 Feb 12. PMID:17296736 doi:10.1128/MCB.02357-06
↑Sidi S, Sanda T, Kennedy RD, Hagen AT, Jette CA, Hoffmans R, Pascual J, Imamura S, Kishi S, Amatruda JF, Kanki JP, Green DR, D'Andrea AA, Look AT. Chk1 suppresses a caspase-2 apoptotic response to DNA damage that bypasses p53, Bcl-2, and caspase-3. Cell. 2008 May 30;133(5):864-77. doi: 10.1016/j.cell.2008.03.037. PMID:18510930 doi:10.1016/j.cell.2008.03.037
↑Lee MY, Kim HJ, Kim MA, Jee HJ, Kim AJ, Bae YS, Park JI, Chung JH, Yun J. Nek6 is involved in G2/M phase cell cycle arrest through DNA damage-induced phosphorylation. Cell Cycle. 2008 Sep 1;7(17):2705-9. Epub 2008 Sep 3. PMID:18728393
↑Yang XH, Shiotani B, Classon M, Zou L. Chk1 and Claspin potentiate PCNA ubiquitination. Genes Dev. 2008 May 1;22(9):1147-52. doi: 10.1101/gad.1632808. PMID:18451105 doi:10.1101/gad.1632808
↑Bahassi EM, Ovesen JL, Riesenberg AL, Bernstein WZ, Hasty PE, Stambrook PJ. The checkpoint kinases Chk1 and Chk2 regulate the functional associations between hBRCA2 and Rad51 in response to DNA damage. Oncogene. 2008 Jun 26;27(28):3977-85. doi: 10.1038/onc.2008.17. Epub 2008 Mar 3. PMID:18317453 doi:10.1038/onc.2008.17
↑Melixetian M, Klein DK, Sorensen CS, Helin K. NEK11 regulates CDC25A degradation and the IR-induced G2/M checkpoint. Nat Cell Biol. 2009 Oct;11(10):1247-53. doi: 10.1038/ncb1969. Epub 2009 Sep 6. PMID:19734889 doi:10.1038/ncb1969
↑Sorensen CS, Melixetian M, Klein DK, Helin K. NEK11: linking CHK1 and CDC25A in DNA damage checkpoint signaling. Cell Cycle. 2010 Feb 1;9(3):450-5. Epub 2010 Feb 3. PMID:20090422
↑Sanchez Y, Wong C, Thoma RS, Richman R, Wu Z, Piwnica-Worms H, Elledge SJ. Conservation of the Chk1 checkpoint pathway in mammals: linkage of DNA damage to Cdk regulation through Cdc25. Science. 1997 Sep 5;277(5331):1497-501. PMID:9278511
↑Shieh SY, Ahn J, Tamai K, Taya Y, Prives C. The human homologs of checkpoint kinases Chk1 and Cds1 (Chk2) phosphorylate p53 at multiple DNA damage-inducible sites. Genes Dev. 2000 Feb 1;14(3):289-300. PMID:10673501
↑Feijoo C, Hall-Jackson C, Wu R, Jenkins D, Leitch J, Gilbert DM, Smythe C. Activation of mammalian Chk1 during DNA replication arrest: a role for Chk1 in the intra-S phase checkpoint monitoring replication origin firing. J Cell Biol. 2001 Sep 3;154(5):913-23. PMID:11535615 doi:10.1083/jcb.200104099
↑Heffernan TP, Simpson DA, Frank AR, Heinloth AN, Paules RS, Cordeiro-Stone M, Kaufmann WK. An ATR- and Chk1-dependent S checkpoint inhibits replicon initiation following UVC-induced DNA damage. Mol Cell Biol. 2002 Dec;22(24):8552-61. PMID:12446774
↑Zhao H, Watkins JL, Piwnica-Worms H. Disruption of the checkpoint kinase 1/cell division cycle 25A pathway abrogates ionizing radiation-induced S and G2 checkpoints. Proc Natl Acad Sci U S A. 2002 Nov 12;99(23):14795-800. Epub 2002 Oct 24. PMID:12399544 doi:10.1073/pnas.182557299
↑Sorensen CS, Syljuasen RG, Falck J, Schroeder T, Ronnstrand L, Khanna KK, Zhou BB, Bartek J, Lukas J. Chk1 regulates the S phase checkpoint by coupling the physiological turnover and ionizing radiation-induced accelerated proteolysis of Cdc25A. Cancer Cell. 2003 Mar;3(3):247-58. PMID:12676583
↑Groth A, Lukas J, Nigg EA, Sillje HH, Wernstedt C, Bartek J, Hansen K. Human Tousled like kinases are targeted by an ATM- and Chk1-dependent DNA damage checkpoint. EMBO J. 2003 Apr 1;22(7):1676-87. PMID:12660173 doi:10.1093/emboj/cdg151
↑Jin J, Shirogane T, Xu L, Nalepa G, Qin J, Elledge SJ, Harper JW. SCFbeta-TRCP links Chk1 signaling to degradation of the Cdc25A protein phosphatase. Genes Dev. 2003 Dec 15;17(24):3062-74. Epub 2003 Dec 17. PMID:14681206 doi:10.1101/gad.1157503
↑Xiao Z, Chen Z, Gunasekera AH, Sowin TJ, Rosenberg SH, Fesik S, Zhang H. Chk1 mediates S and G2 arrests through Cdc25A degradation in response to DNA-damaging agents. J Biol Chem. 2003 Jun 13;278(24):21767-73. Epub 2003 Apr 3. PMID:12676925 doi:10.1074/jbc.M300229200
↑Hassepass I, Voit R, Hoffmann I. Phosphorylation at serine 75 is required for UV-mediated degradation of human Cdc25A phosphatase at the S-phase checkpoint. J Biol Chem. 2003 Aug 8;278(32):29824-9. Epub 2003 May 20. PMID:12759351 doi:10.1074/jbc.M302704200
↑Chen MS, Ryan CE, Piwnica-Worms H. Chk1 kinase negatively regulates mitotic function of Cdc25A phosphatase through 14-3-3 binding. Mol Cell Biol. 2003 Nov;23(21):7488-97. PMID:14559997
↑Pichierri P, Rosselli F. The DNA crosslink-induced S-phase checkpoint depends on ATR-CHK1 and ATR-NBS1-FANCD2 pathways. EMBO J. 2004 Mar 10;23(5):1178-87. Epub 2004 Feb 26. PMID:14988723 doi:10.1038/sj.emboj.7600113
↑Kramer A, Mailand N, Lukas C, Syljuasen RG, Wilkinson CJ, Nigg EA, Bartek J, Lukas J. Centrosome-associated Chk1 prevents premature activation of cyclin-B-Cdk1 kinase. Nat Cell Biol. 2004 Sep;6(9):884-91. Epub 2004 Aug 15. PMID:15311285 doi:10.1038/ncb1165
↑Ou YH, Chung PH, Sun TP, Shieh SY. p53 C-terminal phosphorylation by CHK1 and CHK2 participates in the regulation of DNA-damage-induced C-terminal acetylation. Mol Biol Cell. 2005 Apr;16(4):1684-95. Epub 2005 Jan 19. PMID:15659650 doi:E04-08-0689
↑Sorensen CS, Hansen LT, Dziegielewski J, Syljuasen RG, Lundin C, Bartek J, Helleday T. The cell-cycle checkpoint kinase Chk1 is required for mammalian homologous recombination repair. Nat Cell Biol. 2005 Feb;7(2):195-201. Epub 2005 Jan 23. PMID:15665856 doi:10.1038/ncb1212
↑Huang X, Tran T, Zhang L, Hatcher R, Zhang P. DNA damage-induced mitotic catastrophe is mediated by the Chk1-dependent mitotic exit DNA damage checkpoint. Proc Natl Acad Sci U S A. 2005 Jan 25;102(4):1065-70. Epub 2005 Jan 13. PMID:15650047 doi:10.1073/pnas.0409130102
↑Jin Y, Dai MS, Lu SZ, Xu Y, Luo Z, Zhao Y, Lu H. 14-3-3gamma binds to MDMX that is phosphorylated by UV-activated Chk1, resulting in p53 activation. EMBO J. 2006 Mar 22;25(6):1207-18. Epub 2006 Mar 2. PMID:16511572 doi:10.1038/sj.emboj.7601010
↑Chini CC, Chen J. Repeated phosphopeptide motifs in human Claspin are phosphorylated by Chk1 and mediate Claspin function. J Biol Chem. 2006 Nov 3;281(44):33276-82. Epub 2006 Sep 8. PMID:16963448 doi:10.1074/jbc.M604373200
↑Inoue Y, Kitagawa M, Taya Y. Phosphorylation of pRB at Ser612 by Chk1/2 leads to a complex between pRB and E2F-1 after DNA damage. EMBO J. 2007 Apr 18;26(8):2083-93. Epub 2007 Mar 22. PMID:17380128 doi:10.1038/sj.emboj.7601652
↑Wang X, Kennedy RD, Ray K, Stuckert P, Ellenberger T, D'Andrea AD. Chk1-mediated phosphorylation of FANCE is required for the Fanconi anemia/BRCA pathway. Mol Cell Biol. 2007 Apr;27(8):3098-108. Epub 2007 Feb 12. PMID:17296736 doi:10.1128/MCB.02357-06
↑Sidi S, Sanda T, Kennedy RD, Hagen AT, Jette CA, Hoffmans R, Pascual J, Imamura S, Kishi S, Amatruda JF, Kanki JP, Green DR, D'Andrea AA, Look AT. Chk1 suppresses a caspase-2 apoptotic response to DNA damage that bypasses p53, Bcl-2, and caspase-3. Cell. 2008 May 30;133(5):864-77. doi: 10.1016/j.cell.2008.03.037. PMID:18510930 doi:10.1016/j.cell.2008.03.037
↑Lee MY, Kim HJ, Kim MA, Jee HJ, Kim AJ, Bae YS, Park JI, Chung JH, Yun J. Nek6 is involved in G2/M phase cell cycle arrest through DNA damage-induced phosphorylation. Cell Cycle. 2008 Sep 1;7(17):2705-9. Epub 2008 Sep 3. PMID:18728393
↑Yang XH, Shiotani B, Classon M, Zou L. Chk1 and Claspin potentiate PCNA ubiquitination. Genes Dev. 2008 May 1;22(9):1147-52. doi: 10.1101/gad.1632808. PMID:18451105 doi:10.1101/gad.1632808
↑Bahassi EM, Ovesen JL, Riesenberg AL, Bernstein WZ, Hasty PE, Stambrook PJ. The checkpoint kinases Chk1 and Chk2 regulate the functional associations between hBRCA2 and Rad51 in response to DNA damage. Oncogene. 2008 Jun 26;27(28):3977-85. doi: 10.1038/onc.2008.17. Epub 2008 Mar 3. PMID:18317453 doi:10.1038/onc.2008.17
↑Melixetian M, Klein DK, Sorensen CS, Helin K. NEK11 regulates CDC25A degradation and the IR-induced G2/M checkpoint. Nat Cell Biol. 2009 Oct;11(10):1247-53. doi: 10.1038/ncb1969. Epub 2009 Sep 6. PMID:19734889 doi:10.1038/ncb1969
↑Sorensen CS, Melixetian M, Klein DK, Helin K. NEK11: linking CHK1 and CDC25A in DNA damage checkpoint signaling. Cell Cycle. 2010 Feb 1;9(3):450-5. Epub 2010 Feb 3. PMID:20090422
↑Oza V, Ashwell S, Brassil P, Breed J, Deng C, Ezhuthachan J, Haye H, Horn C, Janetka J, Lyne P, Newcombe N, Otterbien L, Pass M, Read J, Roswell S, Su M, Toader D, Yu D, Yu Y, Valentine A, Webborn P, White A, Zabludoff S, Zheng X. Discovery of a novel class of triazolones as Checkpoint Kinase inhibitors--hit to lead exploration. Bioorg Med Chem Lett. 2010 Sep 1;20(17):5133-8. Epub 2010 Jul 29. PMID:20673630 doi:10.1016/j.bmcl.2010.07.015
