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TOMM20 / Mitochondrial import receptor subunit TOM20 homolog · IHC design guide
Design Immunohistochemistry for TOMM20
Plan chromogenic TOMM20 IHC in paraffin sections using the catalog antibody at 2–5 μg/ml (datasheet A04039-2). Assess granular cytoplasmic staining, with lower signal expected in adipocytes and smooth muscle cells (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
TOMM20 Immunohistochemistry Experimental Design Guide
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before staining
| Expected localisation | Granular cytoplasm (HPA tissue IHC); mitochondrial outer membrane expected (UniProt) | |
| Staining pattern | Granular cytoplasmic staining across tissues (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A04039-2) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | None in HPA (detected in all 45 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections (standard IHC practice; not target-specific) | |
| Caveat | Low staining in adipocytes and smooth muscle cells (HPA tissue IHC) | |
| Regulation | No expression regulator specified (UniProt) | |
| Isoform / epitope | No isoforms or cleavage annotated; residues 25–145 face cytoplasm (UniProt) |
Section 1
Recommended TOMM20 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by 3 published TOMM20 IHC protocols for thyroid and mouse liver sections (PMC4909595; PMC7297855; PMC4663018).
| Sample | Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet A04039-2) |
| Fixation | Image fixative and duration unreported (datasheet A04039-2); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet A04039-2); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A04039-2) |
| Primary antibody | Rabbit anti-TOMM20, 2-5 μg/ml (datasheet A04039-2) |
| Primary incubation | Overnight at 4 °C (datasheet A04039-2) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A04039-2) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | TOMM20-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression with a granular pattern in all tissues. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA, pH 8.0, for the catalog antibody (datasheet A04039-2). The thyroid studies used citrate, pH 6.0, with a different antibody (PMC4909595; PMC4663018).
Section 2
What Is the Expected TOMM20 Staining Pattern?
TOMM20 is anchored in the mitochondrial outer membrane, with residues 25–145 facing the cytoplasm (UniProt Q15388 topology). In paraffin-section IHC, expect granular cytoplasmic staining across tissues, including strong staining in several glandular, neuronal and hematopoietic cell populations (HPA tissue IHC). HPA rates tissue staining “Supported” but reports very low consistency between antibody staining and RNA expression; interpret intensity with that limitation in mind (HPA tissue IHC).
| Discrete granular cytoplasmic staining in the expected cells. | This matches the reported tissue pattern and mitochondrial location (HPA tissue IHC; UniProt Q15388 subcellular location). Judge the pattern within identifiable cells rather than treating an overall dark section as a positive result (general IHC practice). |
| Predominantly nuclear, surface-only or uniformly diffuse staining. | These patterns do not match the reported granular cytoplasmic distribution (HPA tissue IHC). Review staining specificity and section quality before scoring them as TOMM20; compartment mismatch alone does not identify the precise artefact (general IHC practice). |
| Strong staining in a cell population expected to stain weakly. | HPA reports low staining in smooth muscle cells and adipocytes (HPA tissue IHC). Check cell identification, then consider cross-reactivity or endogenous detection activity if staining persists; neither cause is established by this observation alone (general IHC practice). |
| Diffuse colour across tissue or the slide, obscuring cell boundaries. | Background prevents a reliable assessment of the granular cytoplasmic pattern (HPA tissue IHC; general IHC practice). Inspect the negative detection control and compare background inside and outside tissue before assigning cellular positivity (general IHC practice). |
| No signal in a documented high-staining tissue. | High staining is reported in adrenal gland glandular cells, bronchial respiratory epithelial cells and bone marrow hematopoietic cells (HPA tissue IHC). Confirm the sampled cells are present, then review the IHC run; absence of signal alone cannot establish biological loss (general IHC practice). |
💡Expected TOMM20 appearanceCall a result positive when the relevant cells show distinct granular cytoplasmic staining, potentially strong in HPA high-staining populations; isolated nuclear colour or uniform haze is an unexpected pattern (HPA tissue IHC; UniProt Q15388 subcellular location).
| Epitope location | TOMM20 has one membrane-spanning segment at residues 7–24 and a cytoplasm-facing region at 25–145 (UniProt Q15388 topology). Antibody epitope information is needed to predict whether a particular reagent recognizes either region. |
| Tissue and cell context | HPA reports granular cytoplasmic staining across tissues, with high staining in several listed cell populations and low staining in smooth muscle cells and adipocytes (HPA tissue IHC). Compare like cell types when judging intensity. |
| Strength of tissue evidence | Tissue IHC is rated Supported, yet HPA notes very low consistency between antibody staining and RNA expression (HPA tissue IHC). Treat the observed pattern as a guide, not a guarantee of intensity in every specimen. |
| Antibody validation | HPA lists HPA011562 and CAB005585 as Supported for IHC (HPA antibodies). This supports using their reported staining patterns for comparison, but does not establish the performance of a different catalog antibody. |
| IF/ICC Q: What should a positive cell look like? | A: Mitochondrial localization is reported, with ICC-IF images listed for A-431, U-251MG and U2OS (HPA subcellular). This localization informs pattern interpretation; the IF/ICC guide covers its own experimental workflow. |
| Target-specific fixation effect | No TOMM20-specific fixation sensitivity is reported in the supplied UniProt or HPA records. Standard retrieval optimization may be needed for paraffin-section IHC, but these sources cannot predict its effect on TOMM20 staining (general IHC practice). |
| Situation | Likely cause | Next action |
|---|---|---|
| Known high-staining cells remain blank. | The run, detection steps or cell identification may need review; HPA documents high staining in the listed populations (HPA tissue IHC; general IHC practice). | Verify the expected cells in the section and compare a documented high-staining control processed in the same run; review retrieval and detection settings as general IHC variables (general IHC practice). |
| The entire section looks brown, with no clear granules. | Broad background can obscure the reported granular cytoplasmic pattern (HPA tissue IHC; general IHC practice). | Compare with a negative detection control, then review blocking, antibody concentration, washing and chromogen development as general IHC variables (general IHC practice). |
| Nuclei dominate the apparent signal. | A nuclear-dominant pattern conflicts with mitochondrial outer-membrane localization and HPA’s granular cytoplasmic pattern (UniProt Q15388 subcellular location; HPA tissue IHC). | Check counterstain and detection controls, and require a convincing cytoplasmic granular component before scoring TOMM20 positivity (general IHC practice). |
| Smooth muscle cells or adipocytes appear as strong as adjacent high-staining cells. | Those cell types are listed as low-staining by HPA; misidentification, cross-reactivity or endogenous detection activity are possibilities, not diagnoses (HPA tissue IHC; general IHC practice). | Confirm cell boundaries and identity, compare another section, and inspect negative detection controls before interpreting the strong colour (general IHC practice). |
| A high-staining reference tissue gives uneven results between sections. | Target-specific fixation effects are not established by the supplied assay evidence. Verify with a matched IHC source before attributing a result to fixation. | Check whether the same cell population is present and compare section quality and run conditions; avoid assigning the difference to fixation without separate evidence (general IHC practice). |
| The study antibody gives a different pattern from HPA images. | HPA’s Supported IHC status applies to HPA011562 and CAB005585; it does not validate another antibody’s staining pattern (HPA antibodies). | Compare cell types and controls, then assess the study antibody’s own IHC validation before using HPA images to interpret its signal (general IHC practice). |
Experiment evidence
IHC & IF images showing TOMM20 staining
A04039-2 · IHCIHC analysis of TOMM20 using anti-TOMM20 antibody (A04039-2). TOMM20 was detected in a paraffin-embedded section of human lung cancer tissue
A04039-2 · IHCIHC analysis of TOMM20 using anti-TOMM20 antibody (A04039-2). TOMM20 was detected in a paraffin-embedded section of human colon cancer tissu
A04039-2 · IFIF analysis of TOMM20 using anti-TOMM20 antibody (A04039-2). TOMM20 was detected in an immunocytochemical section of Hela cells. Enzyme anti
M04039 · IHCIHC analysis of TOMM20 using anti-TOMM20 antibody (M04039). TOMM20 was detected in a paraffin-embedded section of human colorectal adenocarc
M04039 · IHCIHC analysis of TOMM20 using anti-TOMM20 antibody (M04039). TOMM20 was detected in a paraffin-embedded section of human lung cancer tissue.
M04039 · IFImmunofluorescent analysis using the Antibody at 1:50 dilution.
M04039-1 · IHCHuman cervical carcinoma was stained with anti-TOMM20 rabbit antibody
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000173726-TOMM20/tissue/cerebral+cortex#imid_3009024
HPA · HippocampusHuman Protein Atlas IHC, Hippocampus. Source: https://www.proteinatlas.org/ENSG00000173726-TOMM20/tissue/hippocampal+formation#imid_3009041
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000173726-TOMM20/tissue/colon#imid_3008958
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000173726-TOMM20/tissue/liver#imid_3008959
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA011562; green = TOMM20, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA011562; green = TOMM20, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for TOMM20 IHC & IF
🧪Run bone marrow first and score its hematopoietic cells for TOMM20 staining (HPA: High in bone marrow hematopoietic cells). HPA detects TOMM20 in all 45 scored tissues, so there is no HPA-supported negative tissue; no-primary and isotype controls define background, and any unstained cells within the positive section should resemble that background without being assumed to be validated biological negatives (HPA: no negative tissue rows; TOMM20 detected in all 45 scored tissues).
Positive control tissue: Adrenal gland (Glandular cells, HPA High)
Negative control tissue: None in HPA: TOMM20 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show TOMM20 in A-431, U-251MG, U2OS, with annotated localisation: Mitochondria (enhanced) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control, a host- and clonality-matched isotype control (caption: rabbit primary), and validated TOMM20-knockout material as a biological negative. For bone marrow DAB staining, quench endogenous peroxidase and compare against the no-primary control because hematopoietic cells can contribute peroxidase background (HPA: bone marrow hematopoietic cells; standard IHC practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported, and the selected A04039-2 paraffin-section caption does not state the fixative (selected-SKU tissue-IHC caption). The caption documents heat retrieval in EDTA at pH 8.0, but retrieval dependence is unestablished without a comparison to unretrieved sections (selected-SKU tissue-IHC caption). Whether frozen sections or IF are easier is unreported; ICC-IF images show mitochondrial localization, while endogenous peroxidase in bone marrow remains a practical concern for chromogenic IHC (HPA: subcellular localization and bone marrow hematopoietic cells; standard IHC practice).
HPA tissue IHC evidence for TOMM20
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — Very low consistency between antibody staining and RNA expression data.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | High | Protein (IHC) | HPA → |
| Appendix | Glandular cells | High | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | High | Protein (IHC) | HPA → |
| Breast | Glandular cells | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: TOMM20 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced TOMM20 IHC Tips
Troubleshoot TOMM20 staining in paraffin sections by checking retrieval, compartment pattern, controls, and scoring before interpreting biological differences.
What retrieval should I try first if TOMM20 staining is weak?
Use heat-mediated antigen retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A04039-2). Keep heating and cooling conditions consistent across slides, then compare staining with a known positive section processed in the same run (standard IHC practice). The reported lung cancer image used this retrieval followed by 2 μg/ml antibody overnight at 4°C, so those conditions provide a documented starting point (datasheet A04039-2). If signal remains weak, adjust retrieval duration on adjacent sections while holding antibody concentration and detection constant (standard IHC practice). Assess whether the resulting signal is granular and cytoplasmic before accepting stronger staining as improved detection (HPA: tissue IHC profile).
How should I handle fixation when TOMM20 staining varies between sections?
Record the fixative, tissue thickness, and fixation duration for each specimen, and compare sections processed under matched conditions (standard IHC practice). The selected paraffin-section caption does not state a fixative, so target-specific fixation sensitivity cannot be determined from that experiment (datasheet A04039-2). For prospective samples, use a consistent routine fixation procedure and document any deviations before changing retrieval or antibody concentration (standard IHC practice). Do not attribute variable staining to TOMM20 topology or its phosphoserines without a direct fixation comparison (UniProt Q15388 topology and modified residues). Evaluate each run with a matched positive control and examine morphology alongside granular cytoplasmic signal (HPA: tissue IHC profile; standard IHC practice).
What TOMM20 pattern should I expect in chromogenic tissue sections?
Expect predominantly granular cytoplasmic staining at light-microscope resolution, matching the reported tissue pattern across organs (HPA: tissue IHC profile). TOMM20 resides in the mitochondrial outer membrane, with residues 25–145 facing the cytoplasm, so a mitochondrial distribution is biologically plausible (UniProt Q15388 topology and subcellular location). Compare the granules with cell boundaries and a counterstain before scoring diffuse cytoplasmic color as equivalent signal (standard IHC practice). A brightfield DAB image generally cannot resolve the outer membrane itself, so describe the observed pattern as granular cytoplasmic staining (standard IHC practice). Broad nuclear or extracellular staining warrants review of controls, morphology, and detection background before biological interpretation (UniProt Q15388 subcellular location; standard IHC practice).
Could epitope position or an isoform explain discordant TOMM20 staining?
Check the antibody's documented immunogen or epitope before assigning any staining difference to a particular region (standard IHC practice). The supplied record annotates 0 isoforms and one chain spanning residues 1–145, so it provides no isoform-specific explanation for discordance (UniProt Q15388 isoforms and processing). Its membrane segment spans residues 7–24, whereas residues 25–145 face the cytoplasm; access depends on the antibody's actual epitope (UniProt Q15388 topology). Phosphoserines at residues 135 and 138 are annotated, but the payload does not establish an effect on this antibody's binding (UniProt Q15388 modified residues). Compare matched retrieval conditions and independent controls before interpreting a changed pattern as altered TOMM20 expression (standard IHC practice).
How can I check a TOMM20 IHC pattern using multiplex IF?
Use IF on a matched section as a spatial check, and multiplex with a marker for the cell population being assessed, such as respiratory epithelial cells in bronchus (HPA: High in bronchus respiratory epithelial cells; standard IF practice). Choose a spectrally separated far-red fluorophore around 650 nm and inspect an unstained section to assess tissue autofluorescence (standard IF practice). TOMM20's residues 25–145 face the cytoplasm, so plasma-membrane permeabilisation may be needed for an antibody against that region; the antibody epitope is unspecified here (UniProt Q15388 topology; standard IF practice). Include single-color and secondary-only controls, then compare mitochondrial-looking puncta with the chromogenic granular cytoplasmic pattern rather than treating IF brightness as an IHC score (HPA: tissue IHC profile; standard IF practice).
How do I separate genuine TOMM20 signal from DAB background?
Run a no-primary section through the full detection sequence to reveal secondary-reagent, endogenous peroxidase, or chromogen background (standard IHC practice). A routine peroxidase block, such as 3% hydrogen peroxide, should be assessed with tissue morphology and the no-primary control (standard IHC practice). The reported image used 10% goat serum blocking and a peroxidase-conjugated secondary for 30 minutes at 37°C before DAB development (datasheet A04039-2). Titrate antibody or shorten chromogen development if control sections show diffuse deposit, keeping processing matched across comparisons (standard IHC practice). Accept granular cytoplasmic signal preferentially when it exceeds control background and fits mitochondrial localisation (HPA: tissue IHC profile; UniProt Q15388 subcellular location).
What should I quantify when comparing TOMM20 IHC across specimens? ⚠ ANSWER MARKED FOR VERIFICATION
Define comparable regions and cell populations before scoring, and exclude folds, necrosis, and poorly preserved areas (standard IHC practice). For cell-based analysis, record the percentage of positive cells and an intensity category, or calculate an H-score from intensity-weighted percentages on a 0–300 scale (standard IHC practice). If measuring granular DAB density, report signal per mm² of viable tissue or per counted cell, and subtract matched control background (standard IHC practice). Normalize comparisons to the same cell type, sampled area, staining batch, and image settings because the tissue profile varies by cell population (HPA: tissue IHC profile; standard IHC practice). Report compartment pattern separately from intensity so diffuse color does not inflate a mitochondrial-pattern score (HPA: tissue IHC profile; standard IHC practice).
When is a strong TOMM20 stain biologically credible?
Treat granular cytoplasmic staining in intact cells as the expected pattern, consistent with mitochondrial localisation (HPA: tissue IHC profile; UniProt Q15388 subcellular location). Check the cell type: strong staining is reported in bronchial respiratory epithelial cells, while smooth muscle cells and adipocytes are listed as low (HPA: tissue IHC levels). Nuclear or extracellular DAB, tissue-edge accentuation, and signal concentrated in necrosis call for review of morphology and a no-primary control (UniProt Q15388 subcellular location; standard IHC practice). Residual endogenous enzyme activity can produce DAB deposit, so inspect the peroxidase-block control before calling a marginal area positive (standard IHC practice). Interpret staining against morphology and matched controls because tissue antibody staining has very low consistency with RNA expression data (HPA: reliability description).
Boster reagents
Best TOMM20 / Mitochondrial import receptor subunit TOM20 homolog IHC Antibodies
These anti-TOMM20 antibodies have human tissue IHC images; A04039-2 also has cell and tissue IF images. All list human, mouse, and rat reactivity (catalog captions/reactivity).
Real IHC data
Anti-TOMM20 Antibody ®
Cat # A04039-2
Real IHC data
Anti-TOMM20/Tom20 Rabbit Monoclonal Antibody
Cat # M04039
Real IHC data
Anti-TOMM20 Rabbit Monoclonal Antibody
Cat # M04039-1
A04039-2 shows IHC in human lung cancer, colon cancer, and liver paraffin sections and IF in HeLa cells and human colon cancer paraffin sections (A04039-2 captions); M04039 shows IHC in human colorectal adenocarcinoma and lung cancer paraffin sections (M04039 IHC captions). M04039-1 shows IHC staining of human cervical carcinoma; its caption does not report section processing (M04039-1 IHC caption).
Which to pick: For paraffin tissue IHC, choose A04039-2 for its three documented human tissues or M04039 for a rabbit monoclonal with two documented human tissues (A04039-2 and M04039 IHC captions; catalog clonality). For IF/ICC, A04039-2 has documented HeLa cell and paraffin tissue IF images; M04039 also lists ICC/IF, while M04039-1 lists IF without an IF image in this payload (catalog applications and IF captions). All three list human, mouse, and rat reactivity, but their shown IHC samples are human; the IHC captions do not report a fixative, and M04039-1 does not report whether its section was paraffin embedded (catalog reactivity; IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q15388 (TOM20_HUMAN, Mitochondrial import receptor subunit TOM20 homolog).
- Human Protein Atlas. TOMM20 tissue IHC expression (reliability: Supported).
- Human Protein Atlas. TOMM20 subcellular location (ICC-IF): Localized to the mitochondria..
- Human Protein Atlas. TOMM20 antibody validation summary (2 antibodies).
- Multicompartment metabolism in papillary thyroid cancer. The Laryngoscope 2016 — PMC4909595.
- Estrogen Plays a Crucial Role in Rab9-Dependent Mitochondrial Autophagy, Delaying Arterial Senescence. Journal of the American Heart Association 2021 — PMC8174372.
- BGP-15 Protects Mitochondria in Acute, Acetaminophen Overdose Induced Liver Injury. Pathology oncology research : POR 2020 — PMC7297855.
- Mitochondrial Metabolism as a Treatment Target in Anaplastic Thyroid Cancer. Seminars in oncology 2015 — PMC4663018.
- PubMed PMID:7589431 — UniProt-cited evidence.
- PubMed PMID:7498524 — UniProt-cited evidence.
- PubMed PMID:10548729 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for TOMM20 (Mitochondrial import receptor subunit TOM20 homolog). Expected localisation Granular cytoplasm (HPA tissue IHC); mitochondrial outer membrane expected (UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A04039-2). Validated IHC antibody: A04039-2 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative None in HPA (detected in all 45 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet A04039-2); 2. Fixation: Image fixative and duration unreported (datasheet A04039-2); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat retrieval: EDTA pH 8.0 (datasheet A04039-2); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A04039-2); 8. Primary antibody: Rabbit anti-TOMM20, 2-5 μg/ml (datasheet A04039-2); 9. Primary incubation: Overnight at 4 °C (datasheet A04039-2). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Low staining in adipocytes and smooth muscle cells (HPA tissue IHC); Isoform / epitope: No isoforms or cleavage annotated; residues 25–145 face cytoplasm (UniProt); Regulation: No expression regulator specified (UniProt). Evidence: UniProt Q15388, HPA tissue IHC · Supported, HPA ICC-IF · mitochondria., Datasheet A04039-2, PMC4909595, PMC7297855. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/TOMM20/immunohistochemistry-ihc-guide.