TOM7-1 Antibody

What is TOMM7/TOM7 and what is its significance in mitochondrial research?

TOMM7 (translocase of outer mitochondrial membrane 7 homolog) is a small but crucial component of the mitochondrial outer membrane translocase system. It functions as a regulatory subunit of the TOM40 complex, which serves as the main entry gate for proteins into mitochondria. TOMM7 has a calculated molecular weight of approximately 6 kDa and plays essential roles in regulating protein assembly in the mitochondrial outer membrane .

Recent research has revealed that TOMM7 affects the association of Mdm10 with the TOB core complex, influencing the assembly of β-barrel proteins including Tom40 and porin . Additionally, TOMM7 has been shown to play a critical role in PINK1 stabilization and activation, which has significant implications for Parkinson's disease research .

What experimental applications can TOM7-1 antibody be used for?

TOM7-1 antibody (such as the 15071-1-AP antibody) has been validated for multiple experimental applications:

The antibody shows reactivity with human, mouse, and rat samples, making it versatile for comparative studies across these species .

What protein interactions does TOM7 participate in that researchers should consider when designing experiments?

TOM7 directly interacts with multiple proteins within the mitochondrial import machinery. Site-specific photocross-linking experiments in vivo have revealed that TOM7 directly interacts with TOM40 through its transmembrane segment and with Mdm10 . When designing experiments to study TOM7, researchers should consider these interactions:

• TOM7-TOM40 interaction: Crucial for maintaining TOM complex stability

• TOM7-Mdm10 interaction: Regulates the timing of Tom40 release from the TOB complex

• Role in PINK1-TOM complex formation: TOM7 is essential for PINK1 activation at the TOM complex

Understanding these interactions is vital for proper experimental design and interpretation of results, especially when studying mitochondrial protein import, assembly, or related pathologies.

How does TOM7 influence the assembly dynamics of mitochondrial protein complexes as revealed by Blue Native PAGE?

TOM7 plays a sophisticated role in regulating the assembly dynamics of mitochondrial protein complexes, which can be effectively analyzed using Blue Native PAGE (BN-PAGE). Research has shown that:

• TOM7 depletion slightly reduces the molecular size of the 450-kDa TOM40 complex, while its overexpression does not significantly affect the complex size .

• TOM7 levels inversely regulate the formation of the 350-kDa TOB holo complex. Specifically, TOM7 depletion increases the amount of this complex, while overexpression decreases it .

• The 100-kDa complex containing Mdm10-FLAG is converted to a slightly smaller form in tom7Δ mitochondria, indicating that TOM7 influences Mdm10 association with protein complexes .

When performing BN-PAGE analysis of TOM7-related complexes, researchers should carefully control solubilization conditions (typically using digitonin) and validate results with appropriate controls. For optimal resolution of TOM complex components, a 4-13% gradient gel is recommended, with samples being kept at 4°C throughout preparation to maintain native complex integrity.

What is the mechanistic role of TOM7 in PINK1 activation, and how can researchers experimentally investigate this connection?

TOM7 plays an essential role in PINK1 activation at the TOM complex, with significant implications for Parkinson's disease research. Although AlphaFold modeling does not predict a direct interaction between TOM7 and PINK1, experimental evidence confirms TOM7's critical function in this process .

The mechanism appears to involve TOM7's ability to maintain the stability of the TOM40 core complex. Unlike TOM5 and TOM6, whose deletion shows minimal effect on PINK1 activation, loss of TOM7 largely abolishes PINK1 activation - similar to the effect seen with loss of TOM22, which is crucial for stabilizing the TOM40 dimeric pore structure .

To investigate this connection experimentally, researchers can:

• Use BN-PAGE analysis to visualize the formation of the ~700 kDa PINK1-TOM complex in the presence/absence of TOM7

• Perform immunoblotting with anti-TOM40 and anti-PINK1 antibodies to confirm complex formation

• Assess PINK1 activation using phosphorylated ubiquitin (Ser65) as a readout

• Compare effects of TOM7 deletion to deletion of other small TOM proteins (TOM5, TOM6)

When designing these experiments, it's important to include appropriate controls such as kinase-inactive PINK1 mutants and to validate findings across different cell types, as the role of small TOMs may vary between yeast and mammalian systems .

How can researchers effectively use mutational analysis to study TOM7 function in protein transport and complex assembly?

Mutational analysis offers powerful insights into TOM7 function. Based on the search results, effective approaches include:

• Depletion vs. Overexpression Studies: Researchers can compare tom7Δ mitochondria with Tom7↑ (overexpression) mitochondria to assess opposing effects on complex assembly. For instance, depletion of Tom7 decreases transient accumulation of Tom40 at the TOB complex level, while overexpression enhances it .

• Site-Specific Mutations: For investigating TOM7 interactions, researchers can perform site-directed mutagenesis of specific residues in the transmembrane segment that mediates interaction with Tom40.

• Epitope Tagging: Using HA epitope-tagged versions of Tom7 (Tom7-HA) to replace wild-type Tom7 allows for tracking protein levels when specific anti-Tom7 antibodies are unavailable. Validation studies should confirm that the tagged version functions normally (e.g., no growth defects at 37°C or on nonfermentable medium) .

• Amber Codon Replacement: For in vivo cross-linking studies, researchers can replace specific residues with amber codons (as demonstrated with pYO326/GAL1pro-TOM7(X)amb-HA constructs) .

When designing mutational studies, researchers should include appropriate controls for expression levels and conduct complementary functional assays to validate that observed phenotypes directly result from alterations in TOM7 function rather than secondary effects.

What are the optimal conditions for immunohistochemistry using TOM7-1 antibody?

For optimal immunohistochemistry (IHC) results with TOM7-1 antibody, researchers should consider the following protocol parameters:

Recommended dilution range: 1:20-1:200 for IHC applications

Antigen retrieval options:

• Primary recommendation: TE buffer pH 9.0

• Alternative method: Citrate buffer pH 6.0

Validated positive tissue controls:

• Human gliomas tissue

• Human brain tissue

Methodological considerations:

• The optimal antibody dilution should be determined empirically for each experimental system, as it can be sample-dependent

• For tissues with high background, a blocking step with 3-5% normal serum from the same species as the secondary antibody is recommended

• Incubation times may need adjustment based on tissue type and fixation methods

• Always include positive and negative controls in each experimental run

As with any antibody-based method, researchers should validate the specificity of the TOM7-1 antibody in their specific experimental system and consider examining the validation data gallery provided by the antibody supplier .

What approaches can researchers use to validate TOM7-1 antibody specificity in their experimental systems?

Validating antibody specificity is crucial for reliable research outcomes. For TOM7-1 antibody, researchers can implement the following validation strategies:

• Knockout/Knockdown Controls:

  • Use CRISPR-Cas9 generated TOMM7 knockout cell lines

  • Alternatively, use siRNA/shRNA knockdown of TOMM7

  • The antibody signal should be absent or significantly reduced in these samples

• Overexpression Controls:

  • Generate cell lines stably expressing tagged versions of TOMM7 (e.g., TOMM7-HA or TOMM7-FLAG)

  • Compare antibody recognition with tag-specific antibodies

  • Observe increased signal intensity in overexpression samples

• Cross-Species Reactivity Testing:

  • Test the antibody against samples from multiple species (human, mouse, rat) as the antibody has documented reactivity with these species

  • Compare observed molecular weight (6 kDa) with calculated molecular weight

• Western Blot Analysis:

  • Run positive controls alongside experimental samples

  • Check for a single band at the expected molecular weight (6 kDa)

  • Test with both reducing and non-reducing conditions

• Immunoprecipitation-Mass Spectrometry:

  • Perform IP using the TOM7-1 antibody followed by mass spectrometry to confirm protein identity

  • Compare results with antibodies from different sources or different epitopes

Implementing multiple validation approaches provides stronger evidence for antibody specificity than relying on a single method.

How can researchers optimize Blue Native PAGE protocols for studying TOM7-containing complexes?

Blue Native PAGE (BN-PAGE) is an essential technique for analyzing native protein complexes containing TOM7. Based on the research data, here are specific recommendations for optimizing BN-PAGE protocols for TOM7 studies:

• Sample Preparation:

  • Solubilize mitochondria with digitonin (typically 1% w/v) to maintain native complex integrity

  • Keep samples cold (4°C) throughout preparation

  • Centrifuge at 20,000 × g for 10 minutes to remove insoluble material before loading

• Gel Composition and Running Conditions:

  • Use gradient gels (typically 4-13% or 3-12% acrylamide) for optimal resolution of different sized complexes

  • Include Coomassie Blue G-250 in the cathode buffer at 0.02% initially, then switch to 0.002% after the dye front has migrated one-third of the gel

  • Run at 100V at 4°C until the dye front reaches the bottom of the gel

• Detection Strategies:

  • For TOM40 complex: Use anti-Tom40 antibodies to detect the 450-kDa complex

  • For TOB complex: Anti-FLAG antibodies can be used if working with FLAG-tagged Tom38

  • For Mdm10-containing complexes: Anti-FLAG antibodies if using Mdm10-FLAG, or specific anti-Mdm10 antibodies

• Interpretation Guidelines:

  • In wild-type conditions, expect a 450-kDa TOM40 complex

  • TOM7 depletion slightly reduces the size of this complex

  • Look for changes in the 350-kDa TOB holo complex, which increases with TOM7 depletion

  • The 100-kDa Mdm10-containing complex becomes slightly smaller in tom7Δ mitochondria

• Controls and Comparisons:

  • Include wild-type, TOM7-depleted, and TOM7-overexpressing samples for comparative analysis

  • Consider second-dimension SDS-PAGE to analyze complex composition

When studying PINK1-TOM interactions, researchers should look for the ~700kDa PINK1-TOM complex and an intermediate complex between ~500 kDa and ~700kDa .

What are the critical considerations when designing experiments to study TOM7's role in PINK1 activation and mitophagy?

When designing experiments to investigate TOM7's role in PINK1 activation and mitophagy, researchers should consider the following critical factors:

• Experimental Models:

  • Select appropriate cell types: Both yeast models and mammalian cells (such as HeLa cells) have been successfully used

  • For mammalian studies, consider using PINK1-knockout cell lines (e.g., Flp-In T-REx HeLa PINK1-knockout cells) reconstituted with wild-type or mutant PINK1

• Induction Protocols:

  • Standard mitochondrial depolarization: Treat cells with 10 μM Antimycin A / 1μM Oligomycin (A/O) for 3 hours

  • Include appropriate controls: DMSO vehicle control alongside depolarization treatment

• Detection Methods:

  • Monitor PINK1 activation by assessing phosphorylated ubiquitin levels using anti-ubiquitin pSer65 antibodies

  • Use BN-PAGE to detect PINK1-TOM complex formation (~700 kDa complex)

  • Perform immunoblotting with antibodies against TOM40, TOM20, and PINK1 to verify complex components

• Mutational Approaches:

  • Compare wild-type PINK1 with kinase-inactive mutants

  • Test TOM-binding deficient mutants: CTE (L532A/L539A/L540A) for TOM20-binding and TIR (R83E/R88E/R98E) for TOM70-binding

  • When working with TOM7, consider both deletion and overexpression approaches

• Controls and Validation:

  • Validate antibody specificity using knockout controls

  • Include loading controls appropriate for mitochondrial proteins (e.g., HSP60)

  • For mitophagy assays, use multiple markers (e.g., PINK1 stabilization, Parkin recruitment, mitochondrial protein degradation)

• Technical Considerations:

  • For BN-PAGE analysis, ensure gentle solubilization to maintain complex integrity

  • When working with small proteins like TOM7 (6 kDa), use appropriate gel systems for Western blotting (15-20% acrylamide or Tricine-SDS-PAGE)

  • For in vivo cross-linking studies, carefully optimize cross-linker concentration and exposure times

These considerations will help researchers design robust experiments to elucidate TOM7's specific role in PINK1 activation and downstream mitophagy processes.

What are common challenges when using TOM7-1 antibody in immunohistochemistry and how can they be addressed?

Researchers working with TOM7-1 antibody in immunohistochemistry may encounter several challenges. Here are common issues and their solutions:

• High Background Staining:

  • Solution: Optimize antibody dilution (start with 1:100 and adjust as needed)

  • Increase blocking time and concentration (5% normal serum)

  • Try alternative antigen retrieval methods (switch between TE buffer pH 9.0 and citrate buffer pH 6.0)

  • Include additional washing steps with 0.1% Tween-20 in PBS

• Weak or Absent Signal:

  • Solution: Decrease antibody dilution (try 1:20-1:50 range)

  • Extend primary antibody incubation time (overnight at 4°C)

  • Ensure proper antigen retrieval (extend heating time)

  • Verify tissue fixation conditions (overfixation can mask epitopes)

  • Test with known positive control tissues (human gliomas or brain tissue)

• Non-specific Staining:

  • Solution: Pre-absorb antibody with recombinant protein

  • Use more stringent washing conditions

  • Apply additional blocking with 2% BSA before primary antibody

  • Test specificity with a TOMM7 knockout or knockdown control

• Inconsistent Results Across Experiments:

  • Solution: Standardize all protocol steps (timing, temperature, reagent preparation)

  • Prepare larger volumes of antibody dilutions to use across multiple experiments

  • Document lot numbers and storage conditions

  • Include standard positive controls in each experiment

• Tissue-Specific Issues:

  • Solution: Adjust protocol based on tissue type (brain tissue may require different conditions than other tissues)

  • Consider tissue-specific blocking reagents

  • Optimize section thickness (5-7 μm typically works well)

Remember that optimal conditions may need to be empirically determined for each experimental system, as noted in the product information .

How can researchers analyze the dynamic association of TOM7 with mitochondrial protein complexes?

Analyzing the dynamic association of TOM7 with mitochondrial protein complexes requires specialized techniques and careful experimental design. Based on the research data, here are recommended approaches:

• Time-Course Experiments:

  • Monitor complex formation over time after protein synthesis inhibition or mitochondrial stress

  • Compare wild-type with TOM7 overexpression or depletion conditions

  • Analyze samples at multiple timepoints using BN-PAGE followed by immunoblotting

• In Vivo Cross-linking:

  • Use site-specific photocross-linking with amber codon substitution in TOM7

  • Create constructs like pYO326/GAL1pro-TOM7(X)amb-HA where X represents the residue to be replaced with the amber codon

  • This approach has successfully demonstrated direct interactions between TOM7 and both Tom40 and Mdm10

• Protein Stability Assessment:

  • Compare the half-life of TOM7-interacting proteins in the presence/absence of TOM7

  • Use cycloheximide chase experiments followed by western blotting

  • Monitor degradation rates of complex components over time

• Fluorescence-Based Techniques:

  • Implement Fluorescence Recovery After Photobleaching (FRAP) with fluorescently-tagged TOM components

  • Use Förster Resonance Energy Transfer (FRET) to measure protein proximity in real-time

  • Consider split-GFP complementation assays for direct visualization of protein interactions

• Quantitative Mass Spectrometry:

  • Apply SILAC (Stable Isotope Labeling with Amino acids in Cell culture) or TMT (Tandem Mass Tag) labeling

  • Compare interactomes in wild-type versus TOM7-depleted conditions

  • Measure changes in complex composition following mitochondrial stress

When interpreting results, researchers should consider that TOM7's regulatory effects on Mdm10 association with the TOB complex influence the timing of Tom40 release for subsequent assembly into the TOM40 complex . This temporal regulation is crucial for understanding TOM7's role in mitochondrial protein import and assembly.