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ME2 / NAD-dependent malic enzyme, mitochondrial · IHC design guide
Design Immunohistochemistry for ME2
Plan paraffin-section IHC for ME2 using its granular cytoplasmic tissue pattern (HPA tissue IHC) and mitochondrial matrix location as molecular context (UniProt). Compare staining across cell types and use the catalog antibody’s IHC-P conditions to guide detection.
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
ME2 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) | |
| Staining pattern | Variable granular cytoplasmic staining in all cell types (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A01380-1) | |
| 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 | Staining varies across cell types, complicating scoring (HPA tissue IHC) | |
| Regulation | Expression regulation not annotated (UniProt) | |
| Isoform / epitope | 2 isoforms; epitope coverage is unspecified (UniProt) |
Section 1
Recommended ME2 IHC & IF Protocols
The catalog antibody protocol uses EDTA pH 8.0 retrieval (datasheet: A01380-1). The options below summarize four published ME2 IHC workflows (PMC11555414; PMC7085265; PMC8495273; PMC8351415).
| Sample | Paraffin-embedded human ovarian cancer tissue; fixative not specified (datasheet A01380-1) |
| Fixation | Image fixative and duration unreported (datasheet A01380-1); 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 A01380-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A01380-1) |
| Primary antibody | Rabbit anti-ME2, 0.5-1μg/ml (datasheet A01380-1) |
| Primary incubation | Overnight at 4 °C (datasheet A01380-1) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A01380-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | ME2-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Granular cytoplasmic expression at variable levels in all cell types. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 for the catalog antibody (datasheet: A01380-1). Use citrate retrieval when adapting the published citrate workflows (PMC7085265; PMC8351415).
Section 2
What Is the Expected ME2 Staining Pattern?
ME2 is a mitochondrial matrix protein with no transmembrane segment (UniProt P23368). In paraffin-section IHC, expect granular cytoplasmic staining at variable levels across cell types, with high staining reported in selected glandular, respiratory epithelial, and neuronal cells (HPA tissue IHC: Enhanced). Nuclear or membrane-only staining does not match the expected localization (UniProt P23368; HPA tissue IHC).
| Granular cytoplasmic staining in adrenal or colonic glandular cells (HPA tissue IHC: High). | This fits the mitochondrial matrix localization (UniProt P23368) and the reported tissue pattern (HPA tissue IHC). Judge whether granules follow cell boundaries and whether the counterstain leaves nuclei distinguishable (standard IHC practice). |
| Predominantly nuclear, membrane-only, or smooth extracellular staining. | These compartments conflict with ME2's mitochondrial matrix location (UniProt P23368; HPA subcellular: mitochondria supported). Treat an isolated signal there as possible artefact; compare a known-positive section and detection controls before assigning it to ME2 (standard IHC practice). |
| Strong signal confined to an unexpected cell population, without granular cytoplasm. | Consider cross-reactivity or endogenous chromogenic activity (standard IHC practice). HPA reports variable granular expression across all cell types, so cell identity alone cannot establish a false positive; assess the compartment, controls, and tissue context together (HPA tissue IHC). |
| Uniform haze across cells, stroma, and slide background. | A widespread haze obscures the granular cytoplasmic pattern (HPA tissue IHC). Review blocking, antibody concentration, washing, and detection controls as general IHC checks; this appearance does not establish a ME2-specific biological distribution (standard IHC practice). |
| No signal in adrenal glandular cells or bronchial respiratory epithelial cells (HPA tissue IHC: High). | The run needs review, although a single blank section cannot prove ME2 is absent. Check section integrity, retrieval, antibody and detection performance, then repeat alongside an appropriate control (standard IHC practice). HPA staining levels are reference observations, not guarantees for every specimen. |
💡Expected ME2 appearanceCall a positive result when cell-bound granular cytoplasmic staining is visible, especially in HPA-high glandular or respiratory epithelial cells; isolated nuclear, membrane-only, or diffuse background signal is suspect (HPA tissue IHC; UniProt P23368; standard IHC practice).
| Tissue and cell choice | Adrenal, appendix, colon, duodenum, and endometrial glandular cells are reported High (HPA tissue IHC). Salivary glandular cells and skeletal myocytes are Low, so they are weak comparators rather than verified negatives (HPA tissue IHC). |
| Compartment and epitope interpretation | ME2 resides in the mitochondrial matrix and has no transmembrane segment (UniProt P23368). The supplied record does not map the antibody epitope; it cannot predict whether a particular retrieval condition exposes that epitope. |
| Processing and isoforms | UniProt annotates a 19–584 chain and two isoforms (UniProt P23368). Those facts alone do not establish which form the IHC antibody detects, a staining difference between isoforms, or tissue-specific processing. |
| IHC antibody evidence | HPA008247 and HPA008880 each have Enhanced IHC validation (HPA antibodies). HPA describes tissue IHC reliability as Enhanced, with staining consistent with RNA data (HPA tissue IHC); this supports the reference pattern without validating every new sample or detection system. |
| Antigen retrieval and fixation | No target-specific fixation or retrieval effect is supplied. Select and assess retrieval using the antibody's validated IHC conditions and control sections (standard IHC practice); do not infer fixation sensitivity from HPA staining levels or UniProt annotations. |
| IF/ICC cross-check? | Yes: HPA reports mainly mitochondrial localization, supported by ICC-IF images in A-431, U-251MG, and U2OS (HPA subcellular). Use that result as a localization cross-check; it does not specify an IF protocol for this IHC guide. |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected granular staining is absent from a reported High tissue (HPA tissue IHC). | A failed IHC step is possible; the supplied sources do not identify a ME2-specific fixation failure. | Confirm tissue and cell identity, then review retrieval, antibody application, chromogen development, and a run control (standard IHC practice). |
| Nuclei stain more strongly than cytoplasm. | Nuclear predominance conflicts with the mitochondrial matrix assignment (UniProt P23368; HPA subcellular). | Inspect an HPA-high reference cell population and a detection control; withhold a positive ME2 call if nuclear staining remains isolated (standard IHC practice). |
| Atypical cells stain strongly while expected cells remain blank. | Cross-reactivity is possible, but HPA reports variable expression across cell types (HPA tissue IHC). | Check for granular cytoplasmic localization and compare appropriate control sections before judging the cell population (standard IHC practice). |
| Broad brown precipitate appears despite weak cell detail. | Background or endogenous detection activity may obscure the expected granular pattern (HPA tissue IHC; standard IHC practice). | Review blocking, washing, detection-only controls, and chromogen development; reassess only interpretable cell-bound signal (standard IHC practice). |
| A low-staining tissue is treated as a negative control. | Low is not absent: salivary glandular cells, skeletal myocytes, and adipocytes are listed Low (HPA tissue IHC). | Use such tissue as a relative comparator only; rely on appropriate reagent controls to assess nonspecific signal (standard IHC practice). |
| IF/ICC appears mitochondrial while IHC looks diffuse. | HPA supports mitochondrial ICC-IF localization, whereas diffuse IHC lacks the reported granular pattern (HPA subcellular; HPA tissue IHC). | Review IHC background and compartment controls, then compare localization cautiously across preparations (standard IHC practice). |
Experiment evidence
IHC & IF images showing ME2 staining
A01380-1 · IHCIHC analysis of ME2 using anti-ME2 antibody (A01380-1). ME2 was detected in paraffin-embedded section of human ovarian cancer tissue. Heat m
A01380-1 · IHCIHC analysis of ME2 using anti-ME2 antibody (A01380-1). ME2 was detected in paraffin-embedded section of human rectal cancer tissue. Heat me
A01380-1 · IFIF analysis of ME2 using anti-ME2 antibody (A01380-1). ME2 was detected in immunocytochemical section of Hela cells. Enzyme antigen retrieva
M01380 · IHCM01380 staining ME2 in human kidney tissue sections by Immunohistochemistry (IHC-P -paraformaldehyde-fixed, paraffin-embedded sections). Tis
A01380 · IHCImmunohistochemistry of ME2 in human spleen tissue with ME2 antibody at 5 μg/mL.
A01380 · IFImmunofluorescence of ME2 in human spleen tissue with ME2 antibody at 20 μg/mL.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000082212-ME2/tissue/cerebral+cortex#imid_2585516
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000082212-ME2/tissue/colon#imid_2585450
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000082212-ME2/tissue/liver#imid_2585435
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000082212-ME2/tissue/kidney#imid_2585436
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA008247; green = ME2, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA008247; green = ME2, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for ME2 IHC & IF
🧪Run appendix first and expect its glandular cells to stain (HPA: High in appendix glandular cells). HPA detects ME2 in all 45 scored tissues and lists no negative tissue (HPA: no negative rows); use no-primary and isotype controls for background, and treat any unstained cells on the positive slide as internal background references only, not verified ME2-negative cells.
Positive control tissue: Adrenal gland (Glandular cells, HPA High)
Negative control tissue: None in HPA: ME2 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 ME2 in A-431, U-251MG, U2OS, with annotated localisation: Mitochondria (supported) (HPA subcellular).
Technical controls: Run a secondary-only section, a concentration-matched rabbit IgG isotype control, and ME2 knockout material as a biological negative where available (selected SKU caption: rabbit anti-ME2 antibody). For chromogenic appendix IHC, block endogenous peroxidase and check inflammatory cells for residual signal (standard IHC practice).
⚠️Feasibility: The selected SKU caption reports paraffin sections with heat retrieval in EDTA at pH 8.0, but does not report the fixative; no target-specific fixation window or retrieval comparison is supplied (selected SKU caption: A01380-1). The evidence does not establish whether frozen sections or IF are easier; HPA reports supported mitochondrial localization in ICC-IF, which can guide an IF localization check (HPA: mitochondria supported). In appendix, endogenous peroxidase in inflammatory cells can complicate DAB interpretation (standard IHC practice).
HPA tissue IHC evidence for ME2
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — High 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 → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Cerebellum | Purkinje cells | High | Protein (IHC) | HPA → |
| Cerebral cortex | Neuronal cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: ME2 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced ME2 IHC Tips
Troubleshoot ME2 staining in paraffin sections by checking retrieval, intracellular pattern, controls and scoring before interpreting chromogenic signal.
What retrieval conditions should I start with for ME2 in paraffin sections?
Start with heat mediated retrieval in EDTA at pH 8.0 for the catalog antibody (datasheet A01380-1). The selected paraffin section image used this retrieval before an overnight incubation at 4°C with 1 µg/mL primary antibody (caption A01380-1). If staining is weak, first verify heating, cooling and buffer pH on matched sections, then titrate retrieval time while watching for tissue damage (standard IHC practice). Keep section thickness, detection chemistry and exposure to DAB consistent during that comparison so a change in brown signal can be attributed to retrieval rather than another variable (standard IHC practice).
Could fixation explain weak or uneven ME2 staining?
Target specific fixation sensitivity is unknown because the selected paraffin section caption does not state a fixative (caption A01380-1). Record the fixative, fixation interval and processing history for each specimen, and compare sections processed together when investigating weak staining (standard IHC practice). Underfixation can impair morphology, while prolonged fixation can mask epitopes; neither effect has been established specifically for ME2 here (standard IHC practice). Use the specified EDTA pH 8.0 retrieval on all comparison sections, then adjust one processing variable at a time and check tissue preservation alongside the chromogenic signal (datasheet A01380-1; standard IHC practice).
Where should a credible ME2 signal appear in chromogenic IHC?
Expect granular cytoplasmic staining because ME2 resides in the mitochondrial matrix and has no annotated transmembrane segment (UniProt P23368 topology; HPA tissue IHC profile). HPA reports variable granular cytoplasmic expression across cell types and supports a mitochondrial location by subcellular imaging (HPA tissue IHC; HPA subcellular). At high magnification, judge whether punctate or granular DAB signal sits within intact cell cytoplasm, using the counterstain to define nuclei and tissue architecture (standard IHC practice). A predominantly nuclear or surface rim pattern warrants review of blocking, section quality and controls before it is assigned to ME2 (UniProt P23368 localisation; standard IHC practice).
How do isoforms and processing affect interpretation of this antibody's staining?
ME2 has 2 annotated isoforms, and the annotated mature chain spans residues 19–584 (UniProt P23368 isoforms and processing). Without an epitope sequence or isoform reactivity statement in the supplied product evidence, a positive section cannot be assigned to one isoform (supplied A01380-1 caption; UniProt P23368 isoforms). ME2 also has annotated acetylated lysines, so epitope exposure could depend on where an antibody binds, but no such effect is demonstrated for this antibody (UniProt P23368 modified residues). When a biological claim requires isoform specificity, obtain the antibody's epitope mapping and validate the staining with an appropriate orthogonal assay before scoring it as isoform specific (standard IHC practice).
How should I check ME2 localisation in a companion IF experiment?
Use IF as a companion localisation check while interpreting this page's chromogenic IHC, since ME2 is supported in mitochondria (HPA subcellular). Multiplex the ME2 channel with a mitochondrial marker and a marker for the expected cell type, such as an epithelial marker when examining glandular cells reported as high by HPA (HPA tissue IHC; standard IF practice). Choose a fluorophore and imaging channel with low tissue autofluorescence, and include single channel controls to assess bleed through (standard IF practice). Permeabilise sufficiently for antibody access to a matrix epitope across mitochondrial membranes, then confirm that the resulting pattern agrees with the granular cytoplasmic IHC expectation (UniProt P23368 topology; HPA tissue IHC; standard IF practice).
What should I change when DAB background obscures granular ME2 staining?
Inspect a no primary control and the counterstained tissue before increasing primary antibody concentration, because diffuse DAB can obscure a granular cytoplasmic pattern (standard IHC practice; HPA tissue IHC). The selected image used 10% goat serum blocking, 1 µg/mL primary overnight at 4°C, and a biotin based secondary and DAB workflow (caption A01380-1). If background persists, check the peroxidase block, secondary only control, wash stringency and DAB development time on matched sections (standard IHC practice). With biotin based detection, assess endogenous biotin where appropriate; treat these checks as workflow controls rather than evidence of ME2 expression (caption A01380-1; standard IHC practice).
How should I score heterogeneous ME2 staining across a section? ⚠ ANSWER MARKED FOR VERIFICATION
Define cell populations and regions before scoring, because HPA reports variable granular cytoplasmic expression among cell types (HPA tissue IHC). For cell based analysis, record the percentage of positive cells and an intensity based H-score using one fixed threshold and the same scoring rules across slides (standard IHC practice). If counting positive cells in tissue regions, report density per mm² of viable, evaluable tissue rather than raw counts, and exclude folds and necrosis (standard IHC practice). Normalise comparisons to the relevant cell population or viable tissue area, with matched retrieval, DAB development and image settings, then report biological replicates separately (standard IHC practice).
How can I distinguish true ME2 staining from artefact?
A credible ME2 result is granular within cytoplasm, consistent with its mitochondrial matrix location and the HPA tissue pattern (UniProt P23368 localisation; HPA tissue IHC). Check whether stained cells fit the specimen: HPA reports high signal in adrenal glandular cells and low signal in ovarian stroma cells, while the selected product image shows staining in human ovarian cancer tissue (HPA tissue IHC; caption A01380-1). Be cautious with nuclear or surface rim staining, section edge accentuation and necrotic areas, and compare them with intact central tissue (UniProt P23368 localisation; standard IHC practice). Use no primary and peroxidase block controls to identify detection artefact or endogenous enzyme activity before calling ambiguous DAB signal positive (standard IHC practice).
Boster reagents
Best ME2 / NAD-dependent malic enzyme, mitochondrial IHC Antibodies
The catalog includes ME2 antibodies with IHC images from human spleen, ovarian cancer, and kidney tissue, plus IF images from human spleen, HeLa cells, and intestinal cancer tissue (catalog image captions).
Real IHC data
Anti-ME2 Antibody ®
Cat # A01380-1
Real IHC data
Anti-ME2 Antibody (C-term)
Cat # M01380
Real IHC data
Anti-ME2 Antibody
Cat # A01380
A01380 has human spleen IHC and IF images (A01380 image captions); A01380-1 has paraffin section IHC images from human ovarian cancer and rat intestine, plus IF images from HeLa cells and human intestinal cancer tissue (A01380-1 image captions). M01380 has an IHC-P image from formaldehyde-fixed human kidney tissue (M01380 image caption).
Which to pick: For tissue IHC, choose A01380-1 for its paraffin section images and 0.5–1 μg/mL listed IHC dilution (A01380-1 IHC captions; datasheet: 0.5–1 μg/mL); its IHC captions do not report the fixative (A01380-1 IHC captions). For IF/ICC, choose A01380-1 because both applications are listed and its IF captions show HeLa cells and a human intestinal cancer paraffin section (A01380-1 applications and IF captions); A01380 also has a human spleen IF image, but its IHC caption does not report the fixative (A01380 image captions). For cross-species tissue IHC, A01380-1 has human and rat paraffin section images (A01380-1 IHC captions); M01380 is a mouse monoclonal with human and mouse listed reactivity, but its IHC image shows only paraffin-section human kidney (M01380 catalog entry and IHC caption). The selected A01380-1 tissue-IHC caption documents paraffin sections, but does not specify the fixative (selected-SKU IHC image A01380-1).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P23368 (MAOM_HUMAN, NAD-dependent malic enzyme, mitochondrial).
- Human Protein Atlas. ME2 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. ME2 subcellular location (ICC-IF): Mainly localized to the mitochondria..
- Human Protein Atlas. ME2 antibody validation summary (2 antibodies).
- PRMT1-mediated methylation of ME2 promotes hepatocellular carcinoma growth by inhibiting ubiquitination. Cell death & disease 2024 — PMC11555414.
- Overexpression of Malic Enzyme 2 Indicates Pathological and Clinical Significance in Oral Squamous Cell Carcinoma. International journal of medical sciences 2020 — PMC7085265.
- Malic enzyme 2 promotes the progression of hepatocellular carcinoma via increasing triglyceride production. Cancer medicine 2021 — PMC8495273.
- ME2 Promotes Proneural-Mesenchymal Transition and Lipogenesis in Glioblastoma. Frontiers in oncology 2021 — PMC8351415.
- PubMed PMID:1993674 — UniProt-cited evidence.
- PubMed PMID:11401430 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for ME2 (NAD-dependent malic enzyme, mitochondrial). Expected localisation Granular cytoplasm (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A01380-1). Validated IHC antibody: A01380-1 at 0.5-1μg/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 ovarian cancer tissue; fixative not specified (datasheet A01380-1); 2. Fixation: Image fixative and duration unreported (datasheet A01380-1); 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 A01380-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A01380-1); 8. Primary antibody: Rabbit anti-ME2, 0.5-1μg/ml (datasheet A01380-1); 9. Primary incubation: Overnight at 4 °C (datasheet A01380-1). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Staining varies across cell types, complicating scoring (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope coverage is unspecified (UniProt); Regulation: Expression regulation not annotated (UniProt). Evidence: UniProt P23368, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the mitochondria., Datasheet A01380-1, PMC11555414, PMC7085265. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/ME2/immunohistochemistry-ihc-guide.