c-Jun Mouse mAb Protocol: WB, IHC & IP Applications

c-Jun Mouse mAb is a monoclonal antibody targeting the c-Jun proto-oncogene protein, a key AP-1 transcription factor subunit involved in cell proliferation, differentiation, and stress response, suitable for applications including Western blot, immunohistochemistry, and immunoprecipitation.

Product Name

c-Jun Mouse mAb

SKU

Ab350278

Host Species

Mouse

Antibody Format

Monoclonal Antibody (mAb)

Formulation

PBS only (no carrier protein or preservative added)

Reference Clone

absea #KC-544

Target Protein

c-Jun (AP-1 transcription factor subunit)

Recommended Applications

Western Blot (WB), Immunohistochemistry (IHC), Immunoprecipitation (IP)

Background: c-Jun and Its Biological Significance

c-Jun is a proto-oncogene product and a founding member of the AP-1 (Activator Protein-1) family of transcription factors. It forms homo- or heterodimers with other bZIP-domain proteins, including c-Fos, ATF, and JDP family members, to regulate gene expression in response to a wide variety of extracellular stimuli.

c-Jun is activated primarily through phosphorylation at Ser63 and Ser73 within its N-terminal transactivation domain by c-Jun N-terminal kinases (JNKs). Downstream target genes regulated by c-Jun are involved in critical cellular processes such as proliferation, apoptosis, differentiation, and the cellular stress response.

Dysregulation of c-Jun expression or activity has been documented in numerous cancers and inflammatory conditions, making it an important biomarker and research target. c-Jun Mouse mAb (Ab350278) provides researchers with a reliable tool for detecting endogenous c-Jun protein across a range of experimental formats.

Materials and Reagents Required

• Primary antibody: c-Jun Mouse mAb (Ab350278), formulated in PBS
• Cell/tissue lysate or FFPE tissue sections appropriate to the application
• SDS-PAGE gels and transfer membranes (for Western blot)
• Blocking buffer: 5% non-fat dry milk or 5% BSA in TBST (for WB); serum-based blocking buffer (for IHC)
• Secondary antibody: HRP-conjugated anti-mouse IgG (for WB/IHC) or appropriate fluorescent secondary
• Protein A/G agarose or magnetic beads (for IP)
• RIPA or equivalent lysis buffer supplemented with protease and phosphatase inhibitors
• PBS (pH 7.4) for dilution and washing steps
• Detection substrate: ECL reagent (for WB) or DAB chromogen (for IHC)

Step-by-Step Protocol

Western Blot (WB)

1. Prepare cell or tissue lysates in RIPA buffer containing protease and phosphatase inhibitors on ice. Determine protein concentration by BCA or Bradford assay.
2. Load 20–40 µg total protein per lane on an SDS-PAGE gel (10–12% recommended for c-Jun, ~39 kDa). Run electrophoresis and transfer to PVDF or nitrocellulose membrane.
3. Block membrane with 5% non-fat milk in TBST for 1 hour at room temperature.
4. Incubate with c-Jun Mouse mAb (Ab350278) at the recommended dilution (see manufacturer's datasheet; typically 1:500–1:2000) in blocking buffer overnight at 4°C.
5. Wash membrane 3 × 10 min with TBST.
6. Incubate with HRP-conjugated anti-mouse secondary antibody (1:5000–1:10000) for 1 hour at room temperature.
7. Wash 3 × 10 min with TBST, then detect signal by ECL. Expose to X-ray film or digital imaging system.

Immunohistochemistry (IHC)

1. Deparaffinize and rehydrate FFPE sections. Perform antigen retrieval (citrate buffer, pH 6.0, 95–100°C, 10–20 min, or as required).
2. Block endogenous peroxidase with 3% H₂O₂ for 10 min. Rinse with PBS.
3. Block non-specific binding with 5–10% normal serum (species matched to secondary antibody) for 30–60 min.
4. Apply c-Jun Mouse mAb (Ab350278) at recommended dilution in antibody diluent. Incubate overnight at 4°C in a humidified chamber.
5. Wash 3 × 5 min with PBS. Apply HRP-conjugated anti-mouse secondary antibody for 30–60 min at room temperature.
6. Wash 3 × 5 min with PBS. Develop with DAB chromogen. Monitor under microscope. Counterstain with hematoxylin, dehydrate, and mount.

Immunoprecipitation (IP)

1. Lyse cells in IP-compatible lysis buffer. Preclear lysate with Protein A/G beads for 30 min at 4°C to reduce non-specific binding.
2. Add c-Jun Mouse mAb (Ab350278) to the precleared lysate (typical IP amount: 1–5 µg antibody per 500 µg total protein). Incubate with rotation overnight at 4°C.
3. Add Protein A/G agarose or magnetic beads and continue incubation for 1–2 hours at 4°C.
4. Centrifuge and wash beads 3–4 times with lysis buffer. Elute bound proteins with 2× SDS sample buffer by boiling for 5 min.
5. Resolve by SDS-PAGE and confirm c-Jun immunoprecipitation by Western blot as described above.

Troubleshooting

Problem	Possible Cause	Suggested Solution
No signal on WB	Antibody dilution too high; insufficient antigen; transfer failure	Reduce antibody dilution; verify protein loading; check transfer efficiency with Ponceau S stain
High background	Insufficient blocking; secondary antibody cross-reactivity; too long ECL exposure	Extend blocking time to 2 hours; use 5% BSA instead of milk for phospho-target blots; optimize exposure time
Multiple or unexpected bands	Protein degradation; non-specific binding	Ensure protease inhibitors are added fresh to lysis buffer; optimize antibody dilution; confirm positive control band at ~39 kDa
Weak or absent IHC staining	Insufficient antigen retrieval; over-fixation of tissue	Optimize antigen retrieval conditions; try alternative retrieval buffer (Tris-EDTA, pH 9.0)
High background in IHC	Insufficient peroxidase blocking; non-specific secondary binding	Extend H₂O₂ blocking; use serum from same species as secondary antibody; titrate primary antibody

Storage, Handling and Safety

Storage: Store c-Jun Mouse mAb (Ab350278) at –20°C for long-term storage. For short-term use (up to 1 month), the antibody may be stored at 4°C. Avoid repeated freeze-thaw cycles, which can reduce antibody activity. Aliquoting is recommended upon first thaw.

Formulation note: This antibody is supplied in PBS only, without carrier protein (BSA) or preservatives (such as sodium azide). Researchers should take care when handling the antibody to avoid contamination and should not add sodium azide if the antibody is intended for use in cell-based assays, as azide is toxic to cells.

General safety: Handle all biological reagents in accordance with your institutional biosafety guidelines. Wear appropriate personal protective equipment (PPE) including gloves, lab coat, and eye protection. Dispose of waste reagents in compliance with local regulations.

Frequently asked questions

What applications is c-Jun Mouse mAb (Ab350278) validated for?

c-Jun Mouse mAb (Ab350278) is suitable for Western blot (WB), immunohistochemistry (IHC), and immunoprecipitation (IP). Users should consult the product datasheet for confirmed species reactivity and application-specific dilution ranges, as optimal conditions may vary by sample type.

What is the recommended storage condition for Ab350278?

Ab350278 should be stored at –20°C for long-term storage. For routine short-term use, storage at 4°C for up to one month is acceptable. Aliquot upon first thaw to avoid repeated freeze-thaw cycles that may compromise antibody performance.

Why is the antibody formulated in PBS only, and does this affect experimental use?

Ab350278 is supplied in PBS without carrier protein or preservatives, which makes it compatible with a broad range of downstream applications, including cell-based assays where BSA or azide could interfere. However, users should be aware that without stabilizing additives, the antibody may be more susceptible to degradation upon repeated freeze-thaw; aliquoting is strongly recommended.

What is the expected molecular weight of c-Jun detected by this antibody?

c-Jun protein has a predicted molecular weight of approximately 36–39 kDa; however, it often migrates anomalously on SDS-PAGE gels and may appear at a higher apparent molecular weight (~48 kDa) due to phosphorylation and other post-translational modifications. Researchers should refer to validated WB images on the product datasheet to confirm expected band position.

Which positive control samples are recommended for c-Jun detection?

Cell lines known to express c-Jun at moderate to high levels, such as HeLa, HEK293, or Jurkat cells, are commonly used as positive controls. Treatment of cells with UV irradiation, anisomycin, or TNF-α can further upregulate c-Jun expression and phosphorylation for robust positive controls. Please verify appropriate controls with your specific experimental system.

References

1. Angel P, Karin M. The role of Jun, Fos and the AP-1 complex in cell-proliferation and transformation. Biochimica et Biophysica Acta. 1991;1072(2-3):129-157.
2. Dérijard B, Hibi M, Wu IH, et al. JNK1: a protein kinase stimulated by UV light and Ha-Ras that binds and phosphorylates the c-Jun activation domain. Cell. 1994;76(6):1025-1037.
3. Shaulian E, Karin M. AP-1 as a regulator of cell life and death. Nature Cell Biology. 2002;4(5):E131-E136.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.