Product: Phospho-Chk1 (Ser345) Antibody
Catalog: AF3008
Description: Rabbit polyclonal antibody to Phospho-Chk1 (Ser345)
Application: WB IHC IF/ICC
Reactivity: Human, Mouse, Rat
Prediction: Pig, Zebrafish, Bovine, Horse, Sheep, Rabbit, Dog, Chicken, Xenopus
Mol.Wt.: 55kDa; 54kD(Calculated).
Uniprot: O14757
RRID: AB_2834447

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Product Info

IHC 1:50-1:200, IF/ICC 1:100-1:500, WB 1:500-1:2000
*The optimal dilutions should be determined by the end user.

WB: For western blot detection of denatured protein samples. IHC: For immunohistochemical detection of paraffin sections (IHC-p) or frozen sections (IHC-f) of tissue samples. IF/ICC: For immunofluorescence detection of cell samples. ELISA(peptide): For ELISA detection of antigenic peptide.

Pig(100%), Zebrafish(83%), Bovine(100%), Horse(100%), Sheep(100%), Rabbit(100%), Dog(100%), Chicken(100%), Xenopus(88%)
Phospho-Chk1 (Ser345) Antibody detects endogenous levels of Chk1 only when phosphorylated at Serine 345.
Cite Format: Affinity Biosciences Cat# AF3008, RRID:AB_2834447.
The antibody is from purified rabbit serum by affinity purification via sequential chromatography on phospho-peptide and non-phospho-peptide affinity columns.
Rabbit IgG in phosphate buffered saline , pH 7.4, 150mM NaCl, 0.02% sodium azide and 50% glycerol. Store at -20 °C. Stable for 12 months from date of receipt.


C85740; Cell cycle checkpoint kinase; Checkpoint , S. pombe, homolog of, 1; Checkpoint kinase 1; Checkpoint kinase 1 homolog (S. pombe); CHEK 1; Chek1; Chk 1; Chk1; CHK1 checkpoint homolog (S. pombe); CHK1_HUMAN; EC; rad27; Serine/threonine protein kinase Chk1; Serine/threonine-protein kinase CHK1; STT3, subunit of the oligosaccharyltransferase complex, homolog A (S. cerevisiae);


O14757 CHK1_HUMAN:

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

DNA damage induced protein phosphorylation; regulation of mitotic centrosome separation; regulation of S phase; peptidyl-threonine phosphorylation; DNA repair; chromatin-mediated maintenance of transcription; negative regulation of mitosis;



Score>80(red) has high confidence and is suggested to be used for WB detection. *The prediction model is mainly based on the alignment of immunogen sequences, the results are for reference only, not as the basis of quality assurance.

Model Confidence:
High(score>80) Medium(80>score>50) Low(score<50) No confidence

PTMs - O14757 As Substrate

Site PTM Type Enzyme
T14 Phosphorylation
K43 Ubiquitination
K53 Acetylation
K53 Ubiquitination
K54 Ubiquitination
K60 Ubiquitination
K132 Ubiquitination
K145 Ubiquitination
K166 Ubiquitination
K180 Ubiquitination
K225 Ubiquitination
K233 Ubiquitination
K244 Ubiquitination
K267 Ubiquitination
T279 Phosphorylation
S280 Phosphorylation P31749 (AKT1) , Q15418 (RPS6KA1) , P11309 (PIM1)
S284 Phosphorylation
S286 Phosphorylation P06493 (CDK1) , P24941 (CDK2)
S288 Phosphorylation
S291 Phosphorylation O14757 (CHEK1)
K292 Ubiquitination
S296 Phosphorylation Q13535 (ATR) , O14757 (CHEK1)
S301 Phosphorylation P24941 (CDK2) , P06493 (CDK1)
S305 Phosphorylation
S307 Phosphorylation
S308 Phosphorylation
K313 Ubiquitination
S315 Phosphorylation
S316 Phosphorylation O14757 (CHEK1)
S317 Phosphorylation Q13315 (ATM) , Q13535 (ATR)
T330 Phosphorylation
S331 Phosphorylation
S333 Phosphorylation
S343 Phosphorylation
S345 Phosphorylation Q13535 (ATR) , P41279 (MAP3K8) , Q13315 (ATM)
T348 Phosphorylation
S357 Phosphorylation
T362 Phosphorylation
S365 Phosphorylation
S366 Phosphorylation
K383 Ubiquitination
K388 Ubiquitination
S389 Phosphorylation
K399 Ubiquitination
S407 Phosphorylation
K423 Ubiquitination
K436 Ubiquitination
K445 Ubiquitination
K452 Acetylation
K452 Ubiquitination
K461 Ubiquitination
S467 Phosphorylation
S468 Phosphorylation

PTMs - O14757 As Enzyme

Substrate Site Source
O00716 (E2F3) S124 Uniprot
O14757 (CHEK1) S291 Uniprot
O14757 (CHEK1) S296 Uniprot
O14757 (CHEK1) S316 Uniprot
O15151 (MDM4) S342 Uniprot
O15151 (MDM4) S367 Uniprot
O15294 (OGT) S20 Uniprot
O15350 (TP73) S47 Uniprot
O43395 (PRPF3) S161 Uniprot
O43660 (PLRG1) S119 Uniprot
O60343 (TBC1D4) S485 Uniprot
O60343 (TBC1D4) S588 Uniprot
O75151 (PHF2) S929 Uniprot
O75461 (E2F6) S12 Uniprot
O75461 (E2F6) S52 Uniprot
O95625 (ZBTB11) S511 Uniprot
O95625 (ZBTB11) S537 Uniprot
O95707 (POP4) S10 Uniprot
O95785 (WIZ) S1129 Uniprot
P02545 (LMNA) S307 Uniprot
P04637 (TP53) S15 Uniprot
P04637 (TP53) T18 Uniprot
P04637-1 (TP53) S20 Uniprot
P04637-1 (TP53) S37 Uniprot
P04637 (TP53) S366 Uniprot
P04637 (TP53) S378 Uniprot
P04637 (TP53) T387 Uniprot
P06400 (RB1) S612 Uniprot
P06493 (CDK1) S208 Uniprot
P07814 (EPRS) S910 Uniprot
P10636-8 (MAPT) S262 Uniprot
P11047 (LAMC1) T258 Uniprot
P12956 (XRCC6) S477 Uniprot
P15822 (HIVEP1) S1749 Uniprot
P16989 (YBX3) T112 Uniprot
P18858 (LIG1) S76 Uniprot
P19838 (NFKB1) S328 Uniprot
P22626 (HNRNPA2B1) T159 Uniprot
P25205 (MCM3) S160 Uniprot
P26373 (RPL13) T170 Uniprot
P27816 (MAP4) T925 Uniprot
P30304 (CDC25A) S76 Uniprot
P30304 (CDC25A) S124 Uniprot
P30304-1 (CDC25A) S178 Uniprot
P30304-2 (CDC25A) S239 Uniprot
P30304-2 (CDC25A) S253 Uniprot
P30304-1 (CDC25A) S279 Uniprot
P30304-1 (CDC25A) S293 Uniprot
P30304 (CDC25A) T507 Uniprot
P30305 (CDC25B) S230 Uniprot
P30305 (CDC25B) S563 Uniprot
P30307 (CDC25C) S216 Uniprot
P33992 (MCM5) T633 Uniprot
P35611 (ADD1) S726 Uniprot
P35612 (ADD2) S713 Uniprot
P36507 (MAP2K2) T59 Uniprot
P38936 (CDKN1A) T145 Uniprot
P38936 (CDKN1A) S146 Uniprot
P39748 (FEN1) T195 Uniprot
P43243 (MATR3) S4 Uniprot
P43243 (MATR3) T150 Uniprot
P43243 (MATR3) S195 Uniprot
P43405 (SYK) S295 Uniprot
P46013 (MKI67) T1764 Uniprot
P49761 (CLK3) S157 Uniprot
P49790 (NUP153) S297 Uniprot
P49790 (NUP153) S330 Uniprot
P49792 (RANBP2) T1098 Uniprot
P52272 (HNRNPM) S432 Uniprot
P52292 (KPNA2) S54 Uniprot
P52294 (KPNA1) S18 Uniprot
P54132 (BLM) T182 Uniprot
P54132 (BLM) S539 Uniprot
P54132 (BLM) S646 Uniprot
P55039 (DRG2) S72 Uniprot
P67809 (YBX1) T80 Uniprot
P67870 (CSNK2B) T213 Uniprot
P68431 (HIST1H3J) T12 Uniprot
P84098 (RPL19) S12 Uniprot
P84098 (RPL19) T56 Uniprot
P84243 (H3F3B) T12 Uniprot
P85299 (PRR5) S240 Uniprot
Q00341 (HDLBP) T8 Uniprot
Q02750 (MAP2K1) T55 Uniprot
Q04837 (SSBP1) S67 Uniprot
Q06609-1 (RAD51) T309 Uniprot
Q08AD1 (CAMSAP2) S464 Uniprot
Q12789 (GTF3C1) S667 Uniprot
Q12888 (TP53BP1) S1678 Uniprot
Q13043 (STK4) T340 Uniprot
Q13257 (MAD2L1) S185 Uniprot
Q13257 (MAD2L1) T187 Uniprot
Q13263 (TRIM28) S473 Uniprot
Q13439 (GOLGA4) S71 Uniprot
Q13470 (TNK1) S502 Uniprot
Q13907 (IDI1) S55 Uniprot
Q14004 (CDK13) S437 Uniprot
Q14186 (TFDP1) S23 Uniprot
Q14247 (CTTN) S298 Uniprot
Q14669 (TRIP12) S1078 Uniprot
Q14676 (MDC1) T523 Uniprot
Q14738 (PPP2R5D) S60 Uniprot
Q14966 (ZNF638) S375 Uniprot
Q15648 (MED1) T704 Uniprot
Q16143 (SNCB) Y127 Uniprot
Q16181 (SEPT7) T228 Uniprot
Q16204 (CCDC6) S240 Uniprot
Q16204 (CCDC6) S244 Uniprot
Q27J81 (INF2) S574 Uniprot
Q32P44 (EML3) S176 Uniprot
Q53F19 (NCBP3) S100 Uniprot
Q53H47 (SETMAR) S508 Uniprot
Q5JSZ5 (PRRC2B) S166 Uniprot
Q5JTH9 (RRP12) S1049 Uniprot
Q5T8P6 (RBM26) T839 Uniprot
Q5UIP0 (RIF1) S2205 Uniprot
Q6PD62 (CTR9) S1081 Uniprot
Q6T4R5 (NHS) T401 Uniprot
Q6UB98-2 (ANKRD12) S76 Uniprot
Q7Z2Z1 (TICRR) S865 Uniprot
Q7Z2Z1 (TICRR) S1045 Uniprot
Q7Z2Z1 (TICRR) S1894 Uniprot
Q7Z2Z1 (TICRR) T1898 Uniprot
Q86UE8 (TLK2) S686 Uniprot
Q86UE8 (TLK2) S750 Uniprot
Q86WB0 (ZC3HC1) T84 Uniprot
Q86WR7 (PROSER2) S43 Uniprot
Q8IY67-2 (RAVER1) S700 Uniprot
Q8N4C8 (MINK1) T280 Uniprot
Q8NG66 (NEK11) S273 Uniprot
Q8WWI1 (LMO7) S1510 Uniprot
Q92974 (ARHGEF2) S172 Uniprot
Q96GD4 (AURKB) S331 Uniprot
Q96PK6 (RBM14) S618 Uniprot
Q96PK6 (RBM14) S627 Uniprot
Q96PK6 (RBM14) T629 Uniprot
Q96QD9 (FYTTD1) T205 Uniprot
Q96RL1 (UIMC1) S627 Uniprot
Q96ST3 (SIN3A) T434 Uniprot
Q96T58 (SPEN) T1059 Uniprot
Q99590 (SCAF11) S1127 Uniprot
Q99848 (EBNA1BP2) T182 Uniprot
Q9BQG0 (MYBBP1A) S1310 Uniprot
Q9BRD0 (BUD13) S18 Uniprot
Q9BTD8 (RBM42) S406 Uniprot
Q9BW19 (KIFC1) S26 Uniprot
Q9BXB4 (OSBPL11) S189 Uniprot
Q9BXW9 (FANCD2) S331 Uniprot
Q9BY77 (POLDIP3) S63 Uniprot
Q9GZR7 (DDX24) S82 Uniprot
Q9H0H5 (RACGAP1) S203 Uniprot
Q9H8G2 (CAAP1) S203 Uniprot
Q9H8N7 (ZNF395) S447 Uniprot
Q9HAW4 (CLSPN) T916 Uniprot
Q9HB96 (FANCE) T346 Uniprot
Q9HB96 (FANCE) S374 Uniprot
Q9HC62 (SENP2) S344 Uniprot
Q9NRL2 (BAZ1A) S1320 Uniprot
Q9NRM7 (LATS2) S172 Uniprot
Q9NRM7 (LATS2) S380 Uniprot
Q9NRM7 (LATS2) S408 Uniprot
Q9NRM7 (LATS2) S446 Uniprot
Q9NRM7 (LATS2) S835 Uniprot
Q9NS23-2 (RASSF1) T38 Uniprot
Q9NS23-2 (RASSF1) T43 Uniprot
Q9NS23-2 (RASSF1) S184 Uniprot
Q9NS23 (RASSF1) S188 Uniprot
Q9NUU7 (DDX19A) S92 Uniprot
Q9NWH9 (SLTM) S748 Uniprot
Q9NWH9 (SLTM) S815 Uniprot
Q9NXE8 (CWC25) S337 Uniprot
Q9P2D1 (CHD7) T1227 Uniprot
Q9UEY8 (ADD3) S693 Uniprot
Q9UJM3 (ERRFI1) S251 Uniprot
Q9UJM3 (ERRFI1) S302 Uniprot
Q9UK53-2 (ING1) S126 Uniprot
Q9UKI8-2 (TLK1) S700 Uniprot
Q9UKI8-1 (TLK1) S743 Uniprot
Q9UKI8-2 (TLK1) S764 Uniprot
Q9UKM9 (RALY) T160 Uniprot
Q9UMR2 (DDX19B) S93 Uniprot
Q9UPP1 (PHF8) S904 Uniprot
Q9UQ35 (SRRM2) S1497 Uniprot
Q9UQ35 (SRRM2) S1499 Uniprot
Q9UQ35 (SRRM2) T2252 Uniprot
Q9UQ35 (SRRM2) S2280 Uniprot
Q9UQ35 (SRRM2) S2388 Uniprot
Q9Y2T7 (YBX2) T115 Uniprot
Q9Y3Y2 (CHTOP) T212 Uniprot
Q9Y4F5 (CEP170B) S655 Uniprot
Q9Y520 (PRRC2C) S661 Uniprot
Q9Y570 (PPME1) S15 Uniprot

Research Backgrounds


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.

Endogenous repressor of isoform 1, interacts with, and antagonizes CHK1 to promote the S to G2/M phase transition.


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 induces a change in the conformation of the protein, activates the kinase activity and is a prerequisite for interaction with FBXO6 and subsequent ubiquitination at Lys-436. 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. Phosphorylation at Ser-280 by AKT1/PKB, may promote mono and/or diubiquitination. Also phosphorylated at undefined residues during mitotic arrest, resulting in decreased activity.

Ubiquitinated. Mono or diubiquitination promotes nuclear exclusion (By similarity). The activated form (phosphorylated on Ser-345) is polyubiquitinated at Lys-436 by some SCF-type E3 ubiquitin ligase complex containing FBXO6 promoting its degradation. Ubiquitination and degradation are required to terminate the checkpoint and ensure that activated CHEK1 does not accumulate as cells progress through S phase, when replication forks encounter transient impediments during normal DNA replication.

Subcellular Location:

Nucleus. Cytoplasm. Cytoplasm>Cytoskeleton>Microtubule organizing center>Centrosome.
Note: 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.

Extracellular region or secreted Cytosol Plasma membrane Cytoskeleton Lysosome Endosome Peroxisome ER Golgi apparatus Nucleus Mitochondrion Manual annotation Automatic computational assertionSubcellular location
Tissue Specificity:

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

Subunit Structure:

Interacts (phosphorylated by ATR) with RAD51. Interacts with and phosphorylates CLSPN, an adapter protein that regulates the ATR-dependent phosphorylation of CHEK1. Interacts with BRCA1. Interacts with and phosphorylates CDC25A, CDC25B and CDC25C. Interacts with FBXO6, which regulates CHEK1. Interacts with PPM1D, which regulates CHEK1 through dephosphorylation. Interacts with TIMELESS; DNA damage-dependent. Interacts with FEM1B; activates CHEK1 in response to stress. Interacts with TLK1. Interacts with XPO1 and YWHAZ. Isoform 1 associates with isoform 2, the interaction is disrupted upon phosphorylation by ATR. Interacts with CDK5RAP3; antagonizes CHEK1.


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

Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. NIM1 subfamily.

Research Fields

· Cellular Processes > Cell growth and death > Cell cycle.   (View pathway)

· Cellular Processes > Cell growth and death > p53 signaling pathway.   (View pathway)

· Cellular Processes > Cell growth and death > Cellular senescence.   (View pathway)

· Human Diseases > Infectious diseases: Viral > HTLV-I infection.

· Human Diseases > Cancers: Overview > Viral carcinogenesis.


1). Quercetin inhibits DNA damage responses to induce apoptosis via SIRT5/PI3K/AKT pathway in non-small cell lung cancer. Biomedicine & Pharmacotherapy, 2023 (PubMed: 37390710) [IF=7.5]

Application: WB    Species: Human    Sample: NSCLC cells

Fig. 5. Quercetin inhibited NHEJ and HR pathways phosphorylation. Total proteins lysis and extraction after A549 and H1299 cultured with 0, 12.5, 50, and 200 μM quercetin for 24 h. In NHEJ pathways (A) the expression of p-DNA-PKcsS2056 (B, C), KU70 (D, E) and KU80 (F, G), and in HR pathways (H) the phosphorylation of p-ATRS428 (I, J), p-Chek1S345 (K, L), p-ATMS1981 (M, N) and Chek2T68 (O, P) were detected by western blot in both A549 and H1299 cells. And the results were measured by ImageJ and expressed as protein expression relative to GAPDH (mean ± S.D., n = 3). #p > 0.05, *p 

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