USP9X Antibody

What are the primary applications for USP9X antibodies in research?

USP9X antibodies can be used across multiple applications with varying specificity and efficiency:

• Western Blotting (WB): The most common application, with recommended dilutions ranging from 1:500-1:50000 depending on the antibody

• Immunoprecipitation (IP): Typically requiring 0.5-4.0 μg antibody for 1.0-3.0 mg of total protein lysate

• Immunohistochemistry (IHC): Used at dilutions between 1:20-1:500 for paraffin-embedded tissues

• Immunofluorescence (IF/ICC): Effective at dilutions of 1:10-1:800 depending on the specific antibody

• Flow Cytometry: Successfully used for intracellular staining with optimized protocols

Researchers should note that each antibody shows different performance characteristics across these applications, and validation is essential in your experimental system.

Which species reactivity should I consider when selecting a USP9X antibody?

Most commercial USP9X antibodies show reactivity against:

When working with non-standard research models, select antibodies with documented cross-reactivity or consider sequence homology analysis if reactivity data is unavailable . Some manufacturers note when reactivity is predicted based on sequence homology but not experimentally verified.

How can I confirm the specificity of a USP9X antibody?

To verify antibody specificity, implement these validation methods:

• Knockout/knockdown controls: Several antibodies (ab180191, ab19879) have been validated using USP9X knockout HeLa cells, showing complete loss of signal

• Peptide competition assays: Use blocking peptides (e.g., ab20617) to confirm specific binding

• Multiple antibody comparison: Test antibodies targeting different epitopes of USP9X to confirm consistent patterns

• Expected molecular weight verification: USP9X typically appears at 260-290 kDa, with some fragment bands also detectable

• Immunoprecipitation followed by mass spectrometry: For ultimate confirmation of target identity

For research requiring absolute certainty of specificity, knockout validation represents the gold standard approach.

How can I optimize USP9X co-immunoprecipitation studies to investigate protein-protein interactions?

Co-immunoprecipitation (Co-IP) of USP9X with its interacting partners requires careful optimization:

• Antibody selection: Choose antibodies validated for IP applications with documented Co-IP success (55054-1-AP has been cited in 5 Co-IP publications)

• Buffer composition: For USP9X centrosomal interactions (e.g., with PCM1 or CEP55), use RIPA buffer with protease inhibitors

• Cross-linking considerations: Light cross-linking may preserve transient interactions

• Pull-down protocol:

  • Use 5μg of USP9X antibody with 0.5-3mg of whole cell extract

  • Incubate with protein G magnetic beads under gentle agitation (10 minutes)

  • Add cell lysate and continue incubation (additional 10 minutes)

• Elution and detection: Use SDS loading buffer at 70°C for 10 minutes

Research by Li et al. demonstrated successful Co-IP of USP9X with translation initiation factors using such approaches, showing that USP9X interacts with eIF4B in an mRNA-independent manner .

What are the considerations for studying USP9X localization in centrosomes using immunofluorescence?

USP9X has been identified as an integral component of the centrosome, requiring specific immunofluorescence protocols:

• Fixation method: Both 100% methanol (5 min) and 4% paraformaldehyde (10 min) fixation methods are successful for centrosomal USP9X detection

• Permeabilization: Use 0.1% PBS-Triton X-100 (5 minutes) to access intracellular structures

• Blocking: 1% BSA/10% normal goat serum/0.3M glycine in 0.1% PBS-Tween (1 hour) reduces background

• Co-staining markers: Include centrosomal markers like alpha-tubulin (ab7291) for colocalization studies

• USP9X antibody concentration: 1μg/ml with overnight incubation at 4°C is effective

• Imaging technique: High-content analysis systems (e.g., Operetta CLS) with maximum intensity projection of confocal sections provides optimal visualization

Research by Li et al. established that USP9X physically associates with PCM1 and CEP55 through its N-terminal α-α superhelix domain, which mediates protein-protein interactions .

How should I design experiments to investigate USP9X's role in deubiquitination of specific substrates?

When studying USP9X's deubiquitinating activity on potential substrates:

• Experimental approach sequence:

  • Begin with co-immunoprecipitation to confirm physical interaction

  • Perform USP9X knockdown/knockout to assess effects on substrate stability

  • Analyze ubiquitination status of the suspected substrate with and without USP9X

  • Use recombinant USP9X in in vitro deubiquitination assays for direct evidence

• Controls and variables:

  • Include catalytically inactive USP9X mutants

  • Use proteasome inhibitors (e.g., MG132) to prevent degradation of ubiquitinated proteins

  • Consider the type of ubiquitin linkage (K48 vs. K63) that may be involved

• Case study from literature: Research demonstrated that USP9X deubiquitinates eIF4A1 at lysine-369, protecting it from degradation and thereby regulating translation efficiency. Loss of USP9X increases eIF4A1 ubiquitination and enhances its degradation .

Why might I observe multiple bands with USP9X antibodies in Western blotting, and how should I interpret them?

Multiple bands in USP9X Western blots can have several explanations:

• USP9X fragments: Several documented USP9X fragments exist, including:

  • 289 kDa: Full-length protein (Q93008)

  • 105 kDa: Q6P468 fragment

  • 99.7 kDa: Q59EZ5 protein variant fragment

  • 53.9 kDa: Q86X58 fragment

• Post-translational modifications: USP9X undergoes various modifications that can alter migration patterns

• Proteolytic degradation: Improper sample handling may cause degradation

• Cross-reactivity: Some antibodies may cross-react with USP9Y, especially those targeting conserved regions

To determine which bands represent true USP9X signals:

• Use USP9X knockout lysates as negative controls

• Compare multiple antibodies targeting different epitopes

• Perform peptide competition assays to identify specific bands

• For fragment confirmation, consider mass spectrometry analysis

What are the most common technical issues when using USP9X antibodies for immunohistochemistry, and how can they be resolved?

Common challenges in USP9X immunohistochemistry include:

• Weak or absent staining:

  • Solution: Optimize antigen retrieval using TE buffer pH 9.0 for USP9X detection

  • Alternative: Citrate buffer pH 6.0 may also be effective but typically produces weaker signal

• High background staining:

  • Solution: For neuronal tissues (e.g., hippocampus), use free-floating IHC technique with 4% paraformaldehyde fixation, post-fixation overnight, and 20% sucrose cryoprotection

• Inconsistent results between experiments:

  • Solution: Standardize tissue processing (intracardial perfusion for animal tissues shows superior results)

  • Recommended protocol: For fixed frozen sections, 30μm coronal sections on a cryostat yield optimal results

• Antibody concentration optimization:

  • Starting point: Use 1:50-1:300 dilution range (0.07μg/ml optimal in rat brain sections)

  • Incubation conditions: Overnight at room temperature or 4°C depending on tissue type

Specific protocols have been validated for pancreatic cancer tissue (1:50 dilution) and brain tissue with detailed processing recommendations available in the literature .

How can I troubleshoot poor signal-to-noise ratio in USP9X immunofluorescence experiments?

To improve signal-to-noise ratio in USP9X immunofluorescence:

• Fixation optimization:

  • Methanol fixation (100%, 5 min): Preserves USP9X epitopes while reducing background

  • PFA fixation (4%, 10 min): Alternative method with different epitope exposure characteristics

• Antibody concentration titration:

  • HeLa cells: 1:200-1:800 dilution range for polyclonal antibodies

  • Neuronal cells: More concentrated antibody may be required (1:10-1:100)

• Signal amplification strategies:

  • Use high-sensitivity secondary antibodies (Alexa Fluor® 488/594)

  • Consider tyramide signal amplification for low-abundance detection

• Background reduction techniques:

  • Extended blocking (1 hour) with BSA (1%), normal serum (10%), and glycine (0.3M)

  • Additional washing steps with 0.1% PBS-Tween

• Imaging parameters:

  • Optimize exposure settings to prevent saturation

  • Use confocal microscopy with Z-stacking for centrosomal localization studies

Example protocol producing clear USP9X centrosomal signals: 1μg/ml primary antibody (ab19879), overnight 4°C incubation, followed by 1:1000 Alexa Fluor® 488 secondary antibody .

How can USP9X antibodies be used to investigate its role in the proline biosynthesis pathway and cancer metabolism?

Recent research has identified USP9X as a positive regulator of the proline biosynthesis pathway in non-small cell lung cancer:

• Experimental approach:

  • Use USP9X antibodies (55054-1-AP, 1:5000-1:50000) for Western blot detection in cancer cell lines

  • Combine with PYCR3 antibodies to investigate the USP9X-PYCR3 regulatory axis

  • Perform immunoprecipitation to confirm direct interaction between USP9X and proline cycle enzymes

• Functional studies:

  • Conduct USP9X knockdown experiments followed by metabolic analysis

  • Measure proline cycle activity, pentose phosphate pathway function, and mitochondrial respiration

• Tissue analysis workflow:

  • Compare USP9X expression in tumor vs. normal tissues using IHC (1:50-1:500)

  • Correlate expression with clinical parameters and metabolic markers

Research showed that USP9X stabilizes pyrroline-5-carboxylate reductase 3 (PYCR3), influencing proline biosynthesis and cancer cell growth in vivo. This mechanism identifies a potential therapeutic vulnerability in lung cancer through metabolic pathway targeting .

What is the significance of USP9X in translation regulation, and how can antibodies help study this function?

USP9X has been identified as a regulator of translation through deubiquitination of translation factors:

• Experimental design for investigating USP9X-translation interactions:

  • Use tandem affinity purification with USP9X antibodies to identify associated translation machinery components

  • Perform co-immunoprecipitation with eIF4B and eIF4A1 antibodies

  • Analyze nascent protein synthesis rates after USP9X depletion

• Methodology for studying USP9X effects on specific mRNA translation:

  • Combine polysome profiling with USP9X knockdown/knockout

  • Focus on pro-oncogenic mRNAs (c-Myc, XIAP) reported to be selectively regulated by USP9X

  • Use ribosome profiling for genome-wide translation efficiency analysis

• Tools for investigating the USP9X-eIF4A1 axis:

  • Specific USP9X and eIF4A1 antibodies for co-localization studies

  • Ubiquitination assays focusing on Lys-369 of eIF4A1

  • Translation efficiency reporters to measure functional outcomes

Research demonstrated that USP9X depletion significantly impairs nascent protein synthesis, cap-dependent translation initiation, and cellular proliferation by regulating the stability of eIF4A1 through deubiquitination .

How can researchers investigate USP9X's role in centrosome biology and cell division?

To study USP9X's function in centrosome biogenesis and cell division:

• Centrosome localization studies:

  • Use co-immunofluorescence with USP9X antibodies (ab19879, 1μg/ml) and centrosome markers

  • Employ super-resolution microscopy for precise spatial localization

  • Analyze cell cycle-dependent changes in USP9X centrosomal localization

• Protein stability analysis:

  • Investigate USP9X's role in stabilizing PCM1 and CEP55

  • Perform cyclohexamide chase experiments with/without USP9X to measure half-life of centrosomal proteins

  • Use Western blotting to quantify protein levels after USP9X manipulation

• Functional studies:

  • Conduct centriole duplication assays after USP9X depletion

  • Analyze centrosome maturation defects

  • Examine mitotic spindle formation and chromosome segregation

• Domain interaction mapping:

  • The N-terminal α-α superhelix domain of USP9X mediates its interaction with PCM1 and CEP55

  • Construct domain mutants to disrupt specific interactions

Research established that USP9X is physically associated and spatially co-localized with PCM1 and CEP55 in the centrosome, and either PCM1 or CEP55 loss impairs USP9X centrosome localization, creating a regulatory feedback loop .

How can USP9X antibodies be applied in studying neurodevelopmental disorders and brain function?

USP9X has been implicated in neurodevelopmental disorders, and antibodies can be used to investigate its neuronal functions:

• Brain tissue immunohistochemistry protocols:

  • For rat hippocampus (dentate gyrus): Use 1:300 dilution (0.07μg/ml) of USP9X antibody (ab19879)

  • Fixation method: Intracardial perfusion with 4% paraformaldehyde, post-fixation overnight

  • Section preparation: 30μm coronal sections on a cryostat for free-floating IHC

• Neuronal culture immunofluorescence:

  • Primary neuronal cultures can be stained with 1:50-1:500 dilution of USP9X antibodies

  • Co-staining with neuronal markers helps identify cell type-specific expression patterns

• Research applications:

  • Investigation of USP9X's role in neural stem cell maintenance

  • Analysis of USP9X substrates in neurite outgrowth and synapse formation

  • Examination of USP9X expression in intellectual disability and autism models

Brain-specific applications require careful consideration of fixation and permeabilization conditions, as USP9X epitope accessibility may vary between brain regions and developmental stages.

What are the methodological considerations for multiplexed detection of USP9X and its substrates/interacting partners?

For simultaneous detection of USP9X with its substrates or interacting proteins:

• Antibody compatibility planning:

  • Select primary antibodies from different host species (rabbit anti-USP9X with mouse anti-substrate)

  • Alternatively, use directly conjugated primary antibodies to avoid secondary antibody cross-reactivity

  • Validate each antibody individually before multiplexing

• Multiplexed immunofluorescence approaches:

  • Sequential immunostaining with careful blocking between rounds

  • Tyramide signal amplification for detecting low-abundance interactions

  • Spectral unmixing for closely overlapping fluorophores

• Proximity ligation assay (PLA):

  • Ideal for detecting USP9X-substrate interactions with <40nm proximity

  • Requires validated antibodies for both interacting partners

  • Generates punctate signals representing interacting protein pairs

• Example protocol for USP9X-PCM1 co-detection:

  • Primary antibodies: Anti-USP9X (rabbit, ab19879, 1μg/ml) and anti-PCM1 (mouse)

  • Secondary antibodies: Anti-rabbit Alexa Fluor 488 and anti-mouse Alexa Fluor 594

  • Overnight incubation at 4°C followed by appropriate secondary antibody incubation

This approach has successfully demonstrated co-localization of USP9X with centrosomal proteins PCM1 and CEP55 .

How can researchers integrate USP9X antibody-based studies with functional genomics approaches?

Combining USP9X antibody techniques with functional genomics creates powerful research strategies:

• CRISPR-Cas9 knockout validation:

  • Generate USP9X knockout cell lines as ultimate specificity controls

  • Commercial knockout lysates are available for HeLa cells (ab257790)

  • Use Western blotting with multiple USP9X antibodies to confirm complete knockout

• Domain-specific functional studies:

  • Create CRISPR-mediated domain deletions (e.g., N-terminal α-α superhelix domain)

  • Use antibodies targeting different USP9X regions to confirm expression

  • Correlate with functional outcomes in centrosome biology or translation regulation

• Substrate identification workflow:

  • Combine tandem mass tag (TMT) labeling proteomic analysis with USP9X antibody pull-downs

  • Identify proteins with altered abundance after USP9X depletion

  • Validate candidates through co-immunoprecipitation and functional assays

• Integration with transcriptomics:

  • Correlate USP9X protein levels with mRNA expression profiles

  • Study USP9X impact on translation of specific mRNAs

  • Investigate feedback mechanisms between USP9X activity and gene expression