EIF2B4 Antibody

What is EIF2B4 and why is it important in cellular function?

EIF2B4 is the delta subunit of the eukaryotic translation initiation factor 2B (eIF2B) complex. It plays a crucial role in protein synthesis regulation by catalyzing the exchange of GDP for GTP on the eukaryotic initiation factor 2 (eIF2) gamma subunit . This exchange is essential for translation initiation.

The eIF2B complex's guanine nucleotide exchange factor activity is repressed when bound to eIF2 complex phosphorylated on the alpha subunit, thereby limiting global translation . This regulatory mechanism is vital for cellular adaptation to stress conditions, as it allows cells to modulate protein synthesis rates based on environmental changes and cellular needs .

What applications are EIF2B4 antibodies validated for in research?

EIF2B4 antibodies have been validated for multiple research applications as shown in the following table:

For optimal results, it is recommended that each antibody be titrated in the specific testing system to obtain optimal conditions .

What species reactivity do EIF2B4 antibodies typically show?

Most commercially available EIF2B4 antibodies show reactivity with human and mouse samples . Some antibodies also demonstrate reactivity with rat samples . When selecting an antibody for your research, it's important to verify the specific reactivity claims for your target species:

• Human reactivity: Validated in cell lines such as HeLa, MCF-7, HEK-293T, and K-562

• Mouse reactivity: Validated in mouse skeletal muscle tissue and other mouse samples

• Rat reactivity: Reported for some antibodies but may require additional validation

Cross-reactivity testing should be performed when using these antibodies with species not explicitly validated by the manufacturer.

What is the molecular weight of EIF2B4 and how is this relevant for antibody validation?

The EIF2B4 protein has a calculated molecular weight of 58 kDa (523 amino acids) . This corresponds well with the observed molecular weight of 58 kDa in Western blot applications .

When validating an EIF2B4 antibody, researchers should observe a band at approximately 58 kDa on Western blots. This verification is critical for confirming antibody specificity. Non-specific bands or bands at significantly different molecular weights may indicate cross-reactivity or degradation products. Some antibody documentation reports a size of approximately 60 kDa , which falls within the acceptable margin of variation due to post-translational modifications or differences in gel systems.

How can EIF2B4 antibodies be used to study the integrated stress response (ISR)?

EIF2B4 antibodies can be instrumental in studying the integrated stress response through several methodological approaches:

• Monitoring eIF2B complex assembly: EIF2B4 antibodies can be used in co-immunoprecipitation studies to analyze the assembly state of the eIF2B complex under various stress conditions. Research has shown that eIF2B's assembly state is directly linked to translational output .

• Thermal shift assays: ISRIB, a small molecule that renders cells insensitive to eIF2α phosphorylation, has been shown to specifically stabilize eIF2B4 in cellular extract thermal shift assays (CETSA). Researchers observed an increase in thermal stability of eIF2B4 when lysates were pre-incubated with ISRIB .

• Sucrose gradient analyses: EIF2B4 antibodies can be used to track the sedimentation pattern of eIF2B complexes in sucrose gradients, revealing structural changes in response to pharmacological agents like ISRIB. Studies have shown that ISRIB treatment causes a substantial shift in sedimentation towards higher molecular mass, consistent with doubling of the complex size .

• ISR gene expression studies: Combining EIF2B4 antibody-based protein analysis with transcriptional profiling can reveal relationships between eIF2B function and ISR gene expression. In mouse models with eIF2B dysfunction, activation of ISR genes like ATF4 and EIF4EBP1 has been observed .

What experimental controls should be included when using EIF2B4 antibodies for knockdown/knockout validation studies?

When using EIF2B4 antibodies to validate knockdown or knockout experiments, the following controls are essential:

• Wild-type controls: Include samples from wild-type cells/tissues alongside the knockdown/knockout samples. Research has demonstrated the efficacy of this approach in studies using shRNA libraries targeting eIF2B4 .

• Non-targeting shRNA/siRNA controls: For knockdown experiments, include controls with non-targeting shRNA/siRNA to account for off-target effects. Studies have shown that comparing to negative control shRNA populations provides robust validation .

• Background band monitoring: Some EIF2B4 antibodies detect background bands that can serve as convenient internal controls. As demonstrated in thermal shift assays, a background band that cross-reacts with the anti-eIF2B4 antibody provided a useful internal control when analyzing ISRIB-dependent changes .

• Multiple antibody validation: Due to potential cross-reactivity, validate knockdown/knockout using at least two different antibodies targeting different epitopes of EIF2B4 or use orthogonal methods.

• Functional readouts: Include assays measuring the integrated stress response activation, such as ATF4 reporter systems. Research has shown that knockdown of eIF2B4 renders cells more resistant to ISRIB, confirming the functional importance of eIF2B4 in stress response regulation .

How do mutations in EIF2B4 affect antibody binding and what are the implications for studying vanishing white matter disease?

Mutations in EIF2B4 have been identified in patients with leukoencephalopathy with vanishing white matter (VWM) disease. These mutations can potentially affect antibody binding in several ways:

For VWM disease research, a recommended approach is to:

• Use multiple antibodies targeting different regions of EIF2B4

• Include expression studies comparing wild-type and mutant EIF2B4 (as demonstrated with the R446H mutation)

• Consider complementary approaches such as mass spectrometry for confirming protein levels

• Use tagged expression constructs (e.g., FLAG-tagged EIF2B4) to distinguish between antibody detection issues and actual protein level changes

What methodological considerations are important when using EIF2B4 antibodies in co-immunoprecipitation studies?

When performing co-immunoprecipitation (co-IP) studies with EIF2B4 antibodies, several methodological considerations are critical:

• Buffer composition: The buffer composition can significantly impact eIF2B complex integrity. Research has shown that high-salt buffers can cause dissociation of the eIF2B1 subunit from the rest of the complex . Use physiological salt concentrations when aiming to preserve the entire pentameric complex.

• Crosslinking considerations: Due to potential transient interactions between eIF2B4 and its binding partners, mild crosslinking (e.g., with DSP or formaldehyde) may help preserve interactions, particularly when studying connections with the eIF2 complex.

• Antibody orientation: For co-IP of intact eIF2B complexes, consider using antibodies against other subunits (eIF2B1, eIF2B2, eIF2B3, eIF2B5) and detecting eIF2B4 in the precipitate. This approach can help identify which interactions remain intact under various conditions.

• Detection of phosphorylated eIF2α: When studying the interaction between eIF2B and phosphorylated eIF2α, research has shown that ISRIB antagonizes eIF2-P binding to eIF2B . Include both phospho-specific and total eIF2α antibodies in your analysis.

• Control IPs: Always include control IgG immunoprecipitations as demonstrated in HEK-293T whole cell lysate analyses . This controls for non-specific binding to antibody or beads.

How can EIF2B4 antibodies be used to investigate the mechanism of action of small molecule modulators like ISRIB?

EIF2B4 antibodies are valuable tools for investigating mechanisms of small molecule modulators like ISRIB through several approaches:

• Thermal shift assays: ISRIB has been shown to specifically increase the thermal stability of eIF2B4 in cellular extract thermal shift assays (CETSA), suggesting direct interaction. When lysates were pre-incubated with ISRIB, researchers observed an increase in thermal stability of eIF2B4 but not other eIF2B subunits or translation factors .

• Competitive binding studies: EIF2B4 antibodies can be used in competition experiments with fluorescently labeled ISRIB analogs (e.g., FAM-ISRIB). Research has shown that eIF2α-P, but not eIF2α, competes with FAM-ISRIB for binding to eIF2B .

• Conformational studies: EIF2B4 antibodies can help determine if ISRIB induces conformational changes in the eIF2B complex. Research using sucrose gradients has demonstrated that ISRIB treatment causes a substantial shift in the sedimentation pattern of eIF2B4, consistent with dimerization of the complex .

• Combining genetic and pharmacological approaches: Knockdown of eIF2B4 renders cells resistant to ISRIB, confirming that eIF2B4 is required for ISRIB activity . This approach can be extended to study other small molecule modulators.

A comprehensive experimental design might include:

• Dose-response studies comparing ISRIB analogs with varying potencies

• Time-course analyses of eIF2B complex assembly following drug treatment

• Correlation of structural changes with functional readouts (e.g., ATF4 reporter systems)

• Mutation studies targeting putative ISRIB binding sites on eIF2B4

What are the optimal protocols for Western blot detection of EIF2B4?

For optimal Western blot detection of EIF2B4, researchers should follow these methodological guidelines:

• Sample preparation:

  • Use cell lines with confirmed EIF2B4 expression (e.g., MCF-7, K-562, HeLa, HL-60)

  • Include mouse skeletal muscle tissue as a positive control when working with mouse samples

  • Prepare lysates using complete lysis buffers containing protease inhibitors

• Gel electrophoresis:

  • Use 10-12% SDS-PAGE gels for optimal resolution around the 58 kDa range

  • Load 5-50 μg of total protein per lane (varying amounts may be required depending on expression levels)

• Antibody dilution and incubation:

  • Use EIF2B4 antibodies at 1:500-1:1000 dilution for Western blot

  • For anti-EIF2B4 antibody (ab241573), a concentration of 0.04 μg/mL has been validated

  • Incubate primary antibody overnight at 4°C for optimal sensitivity

• Detection system:

  • ECL detection systems with 10-30 second exposure times have been validated

  • Include loading controls (β-actin, vinculin) as demonstrated in published EIF2B4 research

• Expected results:

  • A specific band at approximately 58 kDa representing EIF2B4

  • Some antibodies may detect background bands that can serve as internal controls

How can researchers design experiments to study the role of EIF2B4 in the integrated stress response pathway?

To study EIF2B4's role in the integrated stress response (ISR) pathway, researchers can design experiments using the following methodological approaches:

• Genetic manipulation strategies:

  • Generate eIF2B4 knockdown/knockout cell lines using shRNA or CRISPR-Cas9

  • Create cell lines expressing EIF2B4 mutants associated with VWM disease (e.g., R374C, R446H)

  • Develop systems for inducible degradation of eIF2B4 (e.g., dTag approaches)

• Reporter systems:

  • Implement ATF4-venus reporter systems for monitoring ISR activation

  • Establish FRET-based sensors to monitor eIF2B complex assembly in living cells

• Pharmacological interventions:

  • Compare effects of ISRIB and other eIF2B activators (e.g., 2BAct)

  • Study the response to various stress inducers (e.g., thapsigargin, tunicamycin)

• Analytical techniques:

  • Monitor eIF2B complex assembly using sucrose gradient centrifugation

  • Analyze protein-protein interactions through co-immunoprecipitation with EIF2B4 antibodies

  • Perform thermal shift assays to study molecular interactions

• Functional readouts:

  • Measure global protein synthesis rates using puromycin incorporation assays

  • Analyze polysome profiles to assess translation efficiency

  • Quantify expression of ISR target genes (ATF4, CHOP, GADD34)

As demonstrated in research with mouse models of VWM disease, treatment with eIF2B activators can abolish ISR induction in affected tissues, highlighting the central role of eIF2B function in this pathway .

What considerations are important when selecting EIF2B4 antibodies for immunohistochemistry applications?

When selecting EIF2B4 antibodies for immunohistochemistry (IHC) applications, researchers should consider:

• Tissue-specific validation:

  • Choose antibodies validated specifically for IHC applications

  • Select antibodies tested on your tissue of interest (e.g., human breast cancer tissue, human testis tissue)

  • Consider species reactivity requirements based on your experimental model

• Antigen retrieval methods:

  • Use TE buffer pH 9.0 for antigen retrieval as suggested in protocols

  • Alternative antigen retrieval may be performed with citrate buffer pH 6.0

  • Optimize retrieval conditions for your specific tissue type

• Dilution optimization:

  • Start with recommended dilution ranges (1:20-1:200 for IHC)

  • Perform titration experiments to determine optimal antibody concentration for your specific tissue

  • Include positive and negative controls for each experiment

• Detection systems:

  • For chromogenic detection, DAB staining has been validated for EIF2B4 IHC

  • Consider amplification systems for detection of low-abundance targets

  • Evaluate background staining carefully, particularly with polyclonal antibodies

• Controls and validation:

  • Include tissues with known EIF2B4 expression levels as positive controls

  • Use isotype controls (e.g., Rabbit IgG for rabbit polyclonal antibodies)

  • Consider peptide competition assays to confirm specificity

Formalin-fixed, paraffin-embedded tissues have been successfully used for EIF2B4 immunohistochemistry, as demonstrated with human colon carcinoma tissue .

What strategies can be employed to validate the specificity of EIF2B4 antibodies in research applications?

To validate the specificity of EIF2B4 antibodies, researchers should employ multiple complementary strategies:

• Genetic knockdown/knockout validation:

  • Use shRNA or CRISPR-Cas9 to reduce or eliminate EIF2B4 expression

  • Confirm reduction in antibody signal correlates with RNA-level knockdown

  • This approach has been successfully used in reporter-based screens with shRNA libraries targeting eIF2B4

• Recombinant protein controls:

  • Express wild-type and mutant EIF2B4 proteins with epitope tags (e.g., FLAG tag)

  • Compare detection between tagged and endogenous proteins

  • Use as positive controls in Western blot and immunoprecipitation applications

• Peptide competition assays:

  • Pre-incubate antibody with immunizing peptide before application

  • Confirm specific signal is eliminated by peptide competition

  • Particularly useful for antibodies raised against synthetic peptides

• Multiple antibody comparison:

  • Test multiple antibodies targeting different epitopes of EIF2B4

  • Compare detection patterns across applications

  • Concordance between different antibodies increases confidence in specificity

• Mass spectrometry validation:

  • Immunoprecipitate EIF2B4 and confirm identity by mass spectrometry

  • Particularly valuable for validating antibodies used in co-IP studies

  • Can identify potential cross-reacting proteins