DNA-dependent protein kinase, catalytic subunit, also known as DNA-PKcs, is an enzyme that in humans is encoded by the gene designated as PRKDC or XRCC7. DNA-PKcs belongs to the phosphatidylinositol 3-kinase-related kinase protein family. The DNA-Pkcs protein is a serine/threonine protein kinase comprising a single polypeptide chain of 4,128 amino acids. DNA-PKcs is the catalytic subunit of a nuclear DNA-dependent serine/threonine protein kinase called DNA-PK. The second component is the autoimmune antigen Ku. On its own, DNA-PKcs is inactive and relies on Ku to direct it to DNA ends and trigger its kinase activity. DNA-PKcs is required for the non-homologous end joining (NHEJ) pathway of DNA repair, which rejoins double-strand breaks. It is also required for V(D)J recombination, a process that utilizes NHEJ to promote immune system diversity. DNA-PKcs knockout mice have severe combined immunodeficiency due to their V(D)J recombination defect. Many proteins have been identified as substrates for the kinase activity of DNA-PK. Autophosphorylation of DNA-PKcs appears to play a key role in NHEJ and is thought to induce a conformational change that allows end processing enzymes to access the ends of the double-strand break.[9] DNA-PK also cooperates with ATR and ATM to phosphorylate proteins involved in the DNA damage checkpoint.
Background References
1. "Frameshift mutation in PRKDC, the gene for DNA-PKcs, in the DNA repair-defective, human, glioma-derived cell line M059J."Anderson C.W., Dunn J.J., Freimuth P.I., Galloway A.M., Allalunis-Turner M.J.Radiat. Res. 156:2-9(2001)
2. "Human DNA-activated protein kinase (DNA-PK) is homologous to phosphatidylinositol kinases."Poltoratsky V.P., Shi X., York J.D., Lieber M.R., Carter T.H.J. Immunol. 155:4529-4533(1995)
Western blot analysis of DNA-PKcs/PRKDC on different lysates with Mouse anti-DNA-PKcs/PRKDC antibody (HA601232) at 1/2,000 dilution.
Lane 1: K-562 cell lysate Lane 2: HepG2 cell lysate Lane 3: HeLa cell lysate Lane 4: Jurkat cell lysate Lane 5: 293T cell lysate Lane 6: HT-29 cell lysate Lane 7: A549 cell lysate Lane 8: MCF7 cell lysate
Lysates/proteins at 20 µg/Lane.
Predicted band size: 469 kDa Observed band size: 469 kDa
Exposure time: 23 seconds;
3-8% SDS-PAGE gel.
Proteins were transferred to a PVDF membrane and blocked with 5% NFDM/TBST for 1 hour at room temperature. The primary antibody (HA601232) at 1/2,000 dilution was used in 5% NFDM/TBST at 4℃ overnight. Goat Anti-Mouse IgG - HRP Secondary Antibody (HA1006) at 1/50,000 dilution was used for 1 hour at room temperature.
Immunohistochemical analysis of paraffin-embedded human colon cancer tissue with Mouse anti-DNA-PKcs/PRKDC antibody (HA601232) at 1/500 dilution.
The section was pre-treated using heat mediated antigen retrieval with sodium citrate buffer (pH 6.0) (high pressure) for 2 minutes. The tissues were blocked in 1% BSA for 20 minutes at room temperature, washed with ddH2O and PBS, and then probed with the primary antibody (HA601232) at 1/500 dilution for 1 hour at room temperature. The detection was performed using an HRP conjugated compact polymer system. DAB was used as the chromogen. Tissues were counterstained with hematoxylin and mounted with DPX.
Immunocytochemistry analysis of HepG2 cells labeling DNA-PKcs/PRKDC with Mouse anti-DNA-PKcs/PRKDC antibody (HA601232) at 1/100 dilution.
Cells were fixed in 4% paraformaldehyde for 20 minutes at room temperature, permeabilized with 0.1% Triton X-100 in PBS for 5 minutes at room temperature, then blocked with 1% BSA in 10% negative goat serum for 1 hour at room temperature. Cells were then incubated with Mouse anti-DNA-PKcs/PRKDC antibody (HA601232) at 1/100 dilution in 1% BSA in PBST overnight at 4 ℃. Goat Anti-Mouse IgG H&L (iFluor™ 488, HA1125) was used as the secondary antibody at 1/1,000 dilution. PBS instead of the primary antibody was used as the secondary antibody only control. Nuclear DNA was labelled in blue with DAPI.
beta Tubulin (ET1602-4, red) was stained at 1/100 dilution overnight at +4℃. Goat Anti-Rabbit IgG H&L (iFluor™ 594, HA1122) were used as the secondary antibody at 1/1,000 dilution.
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