BACKGROUND PDZ-binding kinase/T-LAK cell-originated protein kinase (PBK/TOPK) is a novel MEK3/6-related MAPKK family member that phosphorylates p38 and is involved in H-Ras signaling. During mitosis, TOPK is phosphorylated at Thr9 by Cdk1/cyclin B, and phosphorylation is required for its kinase activity. Moreover, PBK /TOPK was also found to be involved in the spindle midzone formation and cytokinesis by phosphorylation of the microtubule bundling protein, PRC1 at Thr481.1 TOPK expression is regulated by cell cycle-specific transcription factors E2F and CREB/ATF. TOPK is found in activated T/LAK cells, lymphoid tumor cells, and normal testicular tissue. It is highly expressed in hematologic tumors such as leukemia, lymphoma, and myeloma; and its expression corresponds with malignant potential of these tumors. TOPK is also overexpressed in breast cancer and human colorectal cancer and colorectal cancer cell lines. Recent studies suggest a role for TOPK in DNA damage sensing and repair through phosphorylation of histone H2AX.2 Earlier studies showed that TOPK is involved in preventing apoptosis in melanoma cells and is a positive regulator of c-Jun-NH2-kinase 1 (JNK1) signaling and H-Ras induced cell transformation. It was reported that a positive feedback loop between TOPK and ERK2 increases the carcinogenic properties of HCT116 colorectal cancer cells, and therefore TOPK-regulated signaling might be a potential therapeutic target in colorectal cancer. Moreover, recent studies showed that the 25-kDa protein peroxiredoxin 1 (Prx1) is direct target of TOPK. TOPK phosphorylation of Prx1 at Ser32 inhibits UVB-induced apoptosis in RPMI7951 melanoma cells by increasing Prx1 peroxidase activity and decreasing the intracellular accumulation of H2O2.3 In addition, it was demonstrated that PBK/TOPK may contribute to tumor cell development and progression through suppression of p53 function and consequent reductions in the cell-cycle regulatory proteins such as p21.4
1. Abe, Y. et al: J. Mol. Biol. 270:231-45, 2007
2. Zykova, T.A. et al: Clin. Cancer Res. 12:6884-93, 2006
3. Zhang, A.P. et al: Shijie Huaren Xiaohua Zazhi 17: 901-5, 2009
4. Hu, F. et al: Oncogene 2010 Jul 12. [Epub ahead of print] PMID: 20622899
Products are for research use only. They are not intended for human, animal, or diagnostic applications.
Lymphokine-activated killer T-cell-originated protein kinase recombinant protein epitope signature tag (PrEST).
Species & predicted
reactivity ( ):
IF 1-4 µg/ml
Weight of protein:
Detects endogenous PBK/TOPK proteins without cross-reactivity with other family members.
Store at -20°C, 4°C for frequent use. Avoid repeated freeze-thaw cycles.
*Optimal working dilutions must be determined by end user.