CHK1, Active (GWB-5ED06A)





Application Note: Kinase assay Recombinant full-length human CHK1 was expressed by baculovirus in Sf9 insect cells using a N-terminal GST tag.

Function: Required for checkpoint mediated cell cycle arrest in response to DNA damage or the presence of unreplicated DNA. May also negatively regulate cell cycle progression during unperturbed cell cycles. 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. Inhibition of CDC25 activity leads to increased inhibitory tyrosine phosphorylation of CDK-cyclin complexes and blocks cell cycle progression. Binds to and phosphorylates RAD51 at Thr-309, which may enhance the association of RAD51 with chromatin and promote DNA repair by homologous recombination. Binds to and phosphorylates TLK1 at Ser-743, which prevents the TLK1-dependent phosphorylation of the chromatin assembly factor ASF1A. This may affect chromatin assembly during S phase or DNA repair. May also phosphorylate multiple sites within the C-terminus of TP53, which promotes activation of TP53 by acetylation and enhances suppression of cellular proliferation.

Catalytic Activity: ATP + a protein = ADP + a phosphoprotein.

Subunit: Interacts with BRCA1, CLSPN, PPM1D, RAD51, XPO1/CRM1 and YWHAZ/14-3-3 zeta.

Subcellular Location: Nucleus. Cytoplasm. Nuclear export is mediated at least in part by XPO1/CRM1. Also localizes to the centrosome specifically during interphase where it may protect centrosomal CDC2 kinase from inappropriate activation by cytoplasmic CDC25B.

Tissue Specificity: Expressed ubiquitously with the most abundant expression in thymus, testis, small intestine and colon.

Domain: The autoinhibitory region (AIR) inhibits the activity of the kinase domain.

Ptm: Phosphorylated by ATR in a RAD17-dependent manner in response to ultraviolet irradiation and inhibition of DNA replication. Phosphorylated by ATM in response to ionizing irradiation. ATM and ATR can both phosphorylate Ser-317 and Ser-345 and this results in enhanced kinase activity. Phosphorylation at Ser-345 also increases binding to 14-3-3 proteins and promotes nuclear retention. Conversely, dephosphorylation at Ser-345 by PPM1D may contribute to exit from checkpoint mediated cell cycle arrest. May also be phosphorylated at Ser-280 by AKT1/PKB, which may promote mono and/or diubiquitination. Also phosphorylated at undefined residues during mitotic arrest, which results in decreased activity.

Ptm: Ubiquitinated. Mono or diubiquitination promotes nuclear exclusion (By similarity).

Similarity: Belongs to the Ser/Thr protein kinase family. NIM1 subfamily.

Similarity: Contains 1 protein kinase domain. [1] Robinson,H.M., Jones,R., Walker,M., Zachos,G., Brown,R., Cassidy,J. and Gillespie,D.A.
Chk1-dependent slowing of S-phase progression protects DT40 B-lymphoma cells against killing by the nucleoside analogue 5-fluorouracil
[2] Tang,J., Erikson,R.L. and Liu,X., et al.
Checkpoint kinase 1 (Chk1) is required for mitotic progression through negative regulation of polo-like kinase 1 (Plk1)
[3] Mailand,N., Bekker-Jensen,S., Bartek,J. and Lukas,J., et al.
Destruction of Claspin by SCFbetaTrCP restrains Chk1 activation and facilitates recovery from genotoxic stress
[4] Liu,S., Bekker-Jensen,S., Mailand,N., Lukas,C., Bartek,J. and Lukas,J.
Claspin operates downstream of TopBP1 to direct ATR signaling towards Chk1 activation
[5] Bennett,L.N. and Clarke,P.R., et al.
Regulation of Claspin degradation by the ubiquitin-proteosome pathway during the cell cycle and in response to ATR-dependent checkpoint activation
[6] Sanchez Y., Wong C., Thoma R.S., Richman R., Wu Z., Piwnica-Worms H., Elledge S.J.
Conservation of the Chk1 checkpoint pathway in mammals: linkage of DNA damage to Cdk regulation through Cdc25.
[7] Flaggs G., Plug A.W., Dunks K.M., Mundt K.E., Ford J.C., Quiggle M.R.E., Taylor E.M., Westphal C.H., Ashley T., Hoekstra M.F., et al.
Atm-dependent interactions of a mammalian chk1 homolog with meiotic chromosomes.
[8] Semba S., Ouyang H., Han S.-Y., Kato Y., Horii A.
Analysis of the candidate target genes for mutation in microsatellite instability-positive cancers of the colorectum, stomach, and endometrium.
[9] Rieder M.J., Livingston R.J., Braun A.C., Montoya M.A., Chung M.-W., Miyamoto K.E., Nguyen C.P., Nguyen D.A., Poel C.L., Robertson P.D., et al.
NIEHS-SNPs, environmental genome project, NIEHS ES15478, Department of Genome Sciences, Seattle, WA (URL:
[10] Shieh S.-Y., 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.

Additional Information

Name CHK1, Active (GWB-5ED06A)
Related Product Names EC CHK1Serine/threonine-protein kinase Chk1CHEK1
Swissprot ID O14757
NCBI Acc Number NP_001265.1
Molecular Weight 0.5
Source Insect Cells
GI Number 4502803
Stability 1 year at -20 degree C.
Sequence Length 476
Storage Store product at -70 degree C. For optimal storage, aliquot target into smaller quantities after centrifugation and store at recommended temperature.
Datasheets/Manuals Printable datasheet for GWB-5ED06A
Intended Use Research Use Only