tax1bp1b Antibody

What are the validated applications for TAX1BP1 antibodies in cellular research?

TAX1BP1 antibodies have been validated for multiple applications with specific optimal dilutions:

• Western Blot (WB): 1:1000-1:5000 dilution range is typically recommended, though some monoclonal antibodies may be effective at up to 1:50000

• Immunohistochemistry (IHC): 1:250-1:1000 dilution for paraffin-embedded tissues

• Immunofluorescence (IF/ICC): 1:200-1:800 dilution for cellular localization studies

• Immunoprecipitation (IP): Various antibodies are optimized specifically for this application

For precise experimental planning, consider that TAX1BP1 antibodies have shown positive detection in various cell lines including A549, HeLa, HepG2, Jurkat, K-562, HSC-T6, NIH/3T3, and 4T1 cells .

How should researchers optimize western blotting protocols for TAX1BP1 detection?

For optimal western blot detection of TAX1BP1:

• Expected molecular weight considerations: While the calculated molecular weight is 91 kDa, observed weights vary between antibodies. Commonly observed bands appear at 90 kDa, 85 kDa, or 68 kDa depending on the specific antibody and cell type

• Sample preparation: TAX1BP1 is primarily cytoplasmic, so standard cell lysis buffers containing mild detergents are typically sufficient

• Transfer conditions: Use semi-dry or wet transfer methods with methanol-containing buffers for optimal protein transfer

• Blocking: 5% non-fat dry milk in TBST is generally effective, though BSA may provide better results with some antibodies

• Antibody incubation: Primary antibody incubation overnight at 4°C often yields cleaner results than shorter incubations at room temperature

It's advisable to validate antibody specificity using TAX1BP1 knockout cell lines, as PCRP-TAX1BP1-1D4 specificity has been validated by lack of reactivity in TAX1BP1 KO HeLa cells .

How can TAX1BP1 antibodies be utilized to investigate its role in selective autophagy?

TAX1BP1 functions as a selective autophagy receptor involved in xenophagic clearance of pathogenic bacteria and regulation of MAVS aggrephagy . To investigate these functions:

• Co-localization studies: Use immunofluorescence with TAX1BP1 antibodies (1:200-1:800 dilution) alongside markers for:

  • Autophagosomes (LC3-II)

  • Lysosomes (LAMP1)

  • Specific substrates (MAVS, bacterial markers)

• Autophagy flux assays: Monitor TAX1BP1-mediated autophagy by western blotting TAX1BP1 and LC3 conversion in the presence/absence of bafilomycin A1 (BafA1), which inhibits vacuolar acidification and prevents late steps of autophagy flux

• Protein-protein interactions: Use immunoprecipitation with TAX1BP1 antibodies to isolate complexes containing:

  • ATG8-family proteins

  • RB1CC1 (recruited to ubiquitin condensates)

  • NBR1 (found together with TAX1BP1 in protein complexes)

Recent research showed TAX1BP1 phosphorylation promotes its localization to lysosomes, resulting in its degradation through canonical macroautophagy, which can be monitored with appropriate antibodies .

What experimental approaches can detect TAX1BP1 phosphorylation and its functional significance?

TBK1 and IKBKE/IKKi kinases function redundantly to phosphorylate TAX1BP1, regulating its autophagic turnover . To investigate this:

• Phosphorylation detection:

  • Western blotting with phospho-specific antibodies (if available)

  • Phos-tag SDS-PAGE to separate phosphorylated from non-phosphorylated TAX1BP1

  • Immunoprecipitation followed by mass spectrometry for phosphorylation site identification

• Kinase inhibition experiments:

  • Treat cells with TBK1/IKBKE inhibitors and monitor TAX1BP1 phosphorylation status

  • Use kinase-dead mutants of TBK1/IKBKE as controls

• Functional assays:

  • Monitor lysosomal localization using co-immunofluorescence with LAMP1

  • Track TAX1BP1 degradation rates in wild-type versus phospho-mutant constructs

  • Assess MAVS aggrephagy function through semi-denaturing detergent-agarose gel electrophoresis (SDD-AGE)

These approaches can establish connections between TAX1BP1 phosphorylation status and its selective autophagy functions during viral infections or other cellular stress conditions.

How should researchers address multiple band detection when using TAX1BP1 antibodies?

Multiple bands often appear when detecting TAX1BP1, requiring careful interpretation:

• Expected band patterns:

  • Full-length TAX1BP1: ~90-91 kDa

  • Additional bands at 85 kDa and 68 kDa have been reported with validated antibodies

  • TAX1BP1 has 4 reported isoforms; some antibodies recognize both TXBP151-L and TXBP151-S

• Validation strategies:

  • Include positive control lysates from cell lines with known TAX1BP1 expression (A549, HeLa, HepG2)

  • Use TAX1BP1 knockout cell lysates as negative controls

  • Perform siRNA knockdown to confirm band specificity

  • Compare band patterns across multiple validated TAX1BP1 antibodies

• Technical considerations:

  • Use gradient gels (4-15%) for better separation of high molecular weight proteins

  • Optimize transfer conditions for large proteins

  • Consider loading controls appropriate for cytoplasmic proteins

TAX1BP1 degradation during apoptosis may generate additional bands, as it is reportedly degraded by caspase-3-like family proteins upon TNF-induced apoptosis .

What controls are essential for validating TAX1BP1 antibody specificity in immunofluorescence studies?

For rigorous immunofluorescence validation:

• Essential negative controls:

  • TAX1BP1 knockout cells (TAX1BP1 KO HeLa cells have been used for antibody validation)

  • Primary antibody omission

  • Isotype control antibody (matching host species/isotype)

  • siRNA knockdown cells showing reduced signal

• Positive controls:

  • Cell lines with confirmed TAX1BP1 expression (HeLa cells show reliable IF/ICC detection)

  • Cellular conditions that alter TAX1BP1 expression or localization (e.g., TNF stimulation)

• Co-localization validation:

  • Under basal conditions, TAX1BP1 shows diffuse cytoplasmic staining

  • During autophagy induction, co-localization with LC3-positive puncta

  • During virus infection, potential co-localization with MAVS aggregates

• Technical considerations:

  • Fixation method (paraformaldehyde vs. methanol) can affect epitope accessibility

  • Permeabilization optimization (Triton X-100 vs. saponin)

  • Signal amplification methods for low-abundance detection

How can researchers investigate TAX1BP1's role in MHC-II-restricted antigen presentation?

Recent research has revealed TAX1BP1's novel function in presenting endogenous viral antigens to CD4+ T cells . To study this:

• Functional assays:

  • Co-culture experiments with TAX1BP1-silenced antigen-presenting cells and antigen-specific CD4+ T cells

  • Measurement of T cell activation markers or cytokine production

  • Comparison of endogenous vs. exogenous antigen presentation pathways

• Immunoprecipitation approaches:

  • Use TAX1BP1 antibodies to pull down complexes containing MHC-II molecules

  • Analyze interactions with other components of antigen presentation machinery (e.g., calnexin, invariant chain)

  • Mass spectrometry analysis of TAX1BP1 interactome in antigen-presenting cells

• Immunopeptidome analysis:

  • Compare MHC-II-bound peptides in control vs. TAX1BP1-silenced cells

  • Analyze peptide affinity, abundance, and source proteins

  • Assess impact on presentation of specific viral epitopes (HIV Gag, HCMV pp65)

This research area represents an emerging field where TAX1BP1 has been shown to "shape the immunopeptidome of MHC-II molecules" and control "MHC-II molecule peptide loading in particular through its interaction with the cytosolic tail of CANX that stabilizes the invariant chain" .

What experimental approaches can elucidate TAX1BP1's interactions with viral proteins?

TAX1BP1 (originally identified as a Tax1 binding protein) interacts with papillomavirus E2 protein and regulates its stability . To investigate such interactions:

• Protein-protein interaction methods:

  • Co-immunoprecipitation using TAX1BP1 antibodies followed by viral protein detection

  • Reciprocal IP using viral protein antibodies to pull down TAX1BP1

  • Proximity ligation assays for in situ detection of interactions

  • Yeast two-hybrid screening to identify interaction domains

• Functional analysis:

  • Protein stability assays (TAX1BP1 prevents E2 proteasomal degradation)

  • Transcriptional reporter assays (TAX1BP1 functions as a coactivator with p300 in E2-dependent transcription)

  • Ubiquitination assays to detect changes in viral protein ubiquitination status

• Domain mapping:

  • Generate truncation or point mutants of TAX1BP1 to identify critical interaction domains

  • Test ubiquitin-binding-defective TAX1BP1 mutants (UBZ2 and UBZ*) for their ability to interact with viral proteins

In the case of papillomavirus E2, research showed that "TAX1BP1 interacts with both HPV and BPV E2 proteins" through E2's N-terminal transactivation domain (TAD), and this interaction "significantly extends the half-life of E2 proteins by preventing their proteasomal degradation" .

How can TAX1BP1 antibodies be utilized to study its role in T cell activation and metabolic regulation?

TAX1BP1 knockout mice develop splenomegaly and lymphadenopathy, with TAX1BP1 supporting T cell expansion in a cell-autonomous fashion . For investigating these functions:

• T cell activation analysis:

  • Use TAX1BP1 antibodies to monitor protein expression during T cell activation timepoints

  • Compare signaling pathway activation (NF-κB, JNK) in wild-type vs. TAX1BP1-deficient T cells

  • Track proliferation markers in correlation with TAX1BP1 expression levels

• Metabolic profiling:

  • Investigate mTORC1 complex formation in relation to TAX1BP1 expression

  • Monitor 4EBP1 phosphorylation as a downstream readout of mTORC1 activity

  • Analyze autophagy flux using LC3 lipidation as a marker in T cells

• Combined approaches:

  • Adoptive transfer experiments with congenically marked wild-type and TAX1BP1-deficient T cells

  • Ex vivo analysis using TAX1BP1 antibodies to track protein expression in different T cell populations

  • Correlation of TAX1BP1 levels with functional T cell parameters

Research has shown that "TAX1BP1 supports the formation of mTORC1 complexes and mTORC1 dependent translation and phosphorylation of 4EBP1" and that TAX1BP1-deficient T cells exhibit "marked defects in LC3 lipidation," suggesting critical roles in both metabolism and autophagy during T cell activation .

What techniques can detect changes in TAX1BP1 during NF-κB pathway regulation and inflammatory responses?

TAX1BP1 is a negative regulator of NF-κB signaling that interacts with TRAF6 and reduces polyubiquitination of signaling intermediates by recruiting ubiquitin-editing enzymes . To study this:

• Signal-dependent changes:

  • Monitor TAX1BP1 expression, localization, and post-translational modifications after TNF or IL-1 stimulation

  • Track interaction with TRAF6, RIP1, and A20 using co-immunoprecipitation

  • Assess ubiquitination status of binding partners before and after stimulation

• Functional domains analysis:

  • Investigate the role of TAX1BP1's zinc finger domains and "PPXY" motifs in recruiting E3 ligase Itch

  • Examine ubiquitin-binding domain function through mutational analysis

  • Test the impact of these mutations on NF-κB pathway inhibition

• Knockout/knockdown experiments:

  • Compare inflammatory responses in TAX1BP1-deficient vs. wild-type cells

  • Measure NF-κB activation kinetics following various stimuli

  • Assess cytokine production profiles and signaling pathway activation

Research has established that "TAX1BP1 knockout mice exhibit elevated NF-κB activation in response to tumor necrosis factor alpha and interleukin 1 stimulation," highlighting its importance in preventing excessive inflammation and maintaining homeostasis .