PAXX Antibodies

Structure of PAXX

The molecular weight of the protein encoded by the PAXX gene is approximately 25 kDa. This protein is one of the core scaffold proteins in the non-homologous terminal junction (NHEJ) pathway. Its molecular weight is relatively conserved among different mammalian species, with the main differences reflected in the specific domain sequences involved in protein interactions.

The PAXX protein is composed of approximately 230 amino acids, and its three-dimensional structure is shown as a compact spherical fold. The core feature of this protein is that its N-terminal contains an SAP (SAF-A/B, Acinus and PIAS) domain, which can specifically recognize and bind to DNA. The C-terminal of the protein forms a coiled-coil helical bundle, and this secondary structure is crucial for its specific interactions with other key proteins in the NHEJ repair complex, such as the Ku70/Ku80 heterodimer and XLF. This protein network formed through helical and helical interactions is the molecular basis for PAXX to stabilize repair complexes at DNA double-strand breaks and promote terminal joins.

Fig. 1 PAXX and Ku70 schematics showing key functional regions and interactions.¹

Key structural properties of PAXX:

• Contains conserved SAP (SAF-A/B, Acinus and PIAS) domains
• coiled-coil bundle domain with formation of homodimerization
• The C-terminal acid through its regional and NHEJ core complex (such as Ku70 / Ku80) specific interaction

Functions of PAXX

The main function of the protein encoded by the PAXX gene is to participate in the non-homologous end joining (NHEJ) process in DNA double-strand break repair. However, it also plays multiple roles in maintaining genomic stability and the response of cells to DNA damage.

PAXX is not an absolutely essential core factor in the NHEJ pathway. Its function is more similar to that of an efficient "helper" or "enhancer". This enables it to dynamically adjust the fidelity and efficiency of repair in different scenarios such as basic repair and dealing with complex terminal or high-intensity genotoxic stress.

Applications of PAXX and PAXX Antibody in Literature

• Seif-El-Dahan, Murielle, et al. "PAXX binding to the NHEJ machinery explains functional redundancy with XLF." Science advances 9.22 (2023): eadg2834. https://doi.org/10.1126/sciadv.adg2834 

In this study, the structure of the PAXX protein and Ku70/80 complex was resolved by cryo-electron microscopy and crystallography, revealing that PAXX and XLF can simultaneously bind to Ku protein to form DNA-PK dimers of different conformations, synergically promoting the terminal connection of DNA.

• Arora, Mohit, et al. "PAXX, Not NHEJ1 is an independent prognosticator in colon cancer." Frontiers in Molecular Biosciences 7 (2020): 584053. https://doi.org/10.3389/fmolb.2020.584053 

Research has found that in colon cancer, the expression of NHEJ pathway genes such as PAXX and XRCC5 is abnormal. High expression of PAXX is independently associated with poor prognosis in patients. Hypomethylation of its promoter may drive its overexpression and is related to changes in the tumor immune microenvironment.

• Gluza, Joanna, et al. "PAXX/Ku interaction is rate limiting for repair of double-strand DNA breaks requiring end processing." Journal of Biological Chemistry 301.8 (2025). https://doi.org/10.1016/j.jbc.2025.110481

Research has found that a key amino acid mutation in the PAXX protein can significantly stabilize the DNA repair complex and accelerate the repair of DNA double-strand breaks requiring terminal treatment, revealing that the stability of the repair complex is a key rate-limiting step in regulating the repair speed of NHEJ.

• Liu, Xiangyu, et al. "PAXX promotes KU accumulation at DNA breaks and is essential for end-joining in XLF-deficient mice." Nature communications 8.1 (2017): 13816. https://doi.org/10.1038/ncomms13816 

Research reveals that PAXX and XLF are functionally complementary in the DNA repair pathway NHEJ. Paxx-deficient mice rely on XLF, and vice versa. Double deletion leads to embryo death. Mechanistically, PAXX promotes the enrichment of KU protein at the fracture site, while XLF enhances LIG4 recruitment, jointly ensuring repair.

• Craxton, Andrew, et al. "PAXX and its paralogs synergistically direct DNA polymerase λ activity in DNA repair." Nature communications 9.1 (2018): 3877. https://doi.org/10.1038/s41467-018-06127-y

Research has found that PAXX and its homologous proteins XRCC4 and XLF can directly bind to and activate DNA polymerase λ (Pol λ), cooperatively promoting its recruitment to DNA damage sites and the connection of incompatible ends, and jointly regulating the function of polymerase in NHEJ repair.

Creative Biolabs: PAXX Antibodies for Research

Creative Biolabs specializes in the production of high-quality PAXX antibodies for research and industrial applications. Our portfolio includes monoclonal antibodies tailored for ELISA, Flow Cytometry, Western blot, immunohistochemistry, and other diagnostic methodologies.

• Custom PAXX Antibody Development: Tailor-made solutions to meet specific research requirements.
• Bulk Production: Large-scale antibody manufacturing for industry partners.
• Technical Support: Expert consultation for protocol optimization and troubleshooting.
• Aliquoting Services: Conveniently sized aliquots for long-term storage and consistent experimental outcomes.

For more details on our PAXX antibodies, custom preparations, or technical support, contact us at email.