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CPT2 / Carnitine O-palmitoyltransferase 2, mitochondrial · IHC design guide
Design Immunohistochemistry for CPT2
Plan CPT2 paraffin IHC with a 1:50 catalog antibody dilution (datasheet M02112). Compare cytoplasmic staining in high-staining glandular cells with adipocytes showing no detected staining (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CPT2 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 | Cytoplasmic tissue staining (HPA tissue IHC); mitochondrial inner membrane (UniProt) | |
| Staining pattern | Cytoplasmic staining in most tissues; high in some glandular cells (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet M02112) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep paraffin tissue fixation consistent (standard IHC practice; not target-specific) | |
| Caveat | Adipocytes have no detected staining (HPA tissue IHC) | |
| Regulation | Liver-enhanced RNA; IHC effect unknown (HPA RNA) | |
| Isoform / epitope | No isoforms annotated; mature chain spans aa 26–658 (UniProt) |
Section 1
Recommended CPT2 IHC & IF Protocols
The catalog antibody has an IHC-P protocol (datasheet M02112). Two published CPT2 paraffin-section IHC protocols provide additional examples (PMC11308078; PMC13297011).
| Sample | Paraffin-embedded human acinic cell carcinoma of parotid tissue; fixative not specified (datasheet M02112) |
| Fixation | Image fixative and duration unreported (datasheet M02112); 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 M02112); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet M02112) |
| Primary antibody | Rabbit monoclonal (clone FGB-3) anti-CPT2, 1:50 (datasheet M02112) |
| Primary incubation | Overnight at 4 °C (datasheet M02112) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet M02112) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | CPT2-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval for the catalog antibody (datasheet M02112). Citrate pH 6.0 was used in one published protocol (PMC13297011).
Section 2
What Is the Expected CPT2 Staining Pattern?
CPT2 resides at the mitochondrial inner membrane, with annotated matrix-facing regions (UniProt P23786 topology). On paraffin sections, expect predominantly cytoplasmic staining in HPA-positive cells, including glandular cells of the colon and stomach, kidney collecting ducts, and placental syncytiotrophoblasts (HPA tissue IHC). HPA rates tissue IHC reliability as Enhanced, while reporting medium consistency between staining and RNA expression (HPA tissue IHC).
| Cytoplasmic staining in colon glandular cells or kidney collecting ducts (HPA tissue IHC). | This matches HPA's High staining in those cell populations (HPA tissue IHC). A punctate cytoplasmic appearance is compatible with mitochondrial localization (UniProt P23786; HPA subcellular), but chromogenic IHC alone cannot resolve the inner membrane. |
| Predominantly nuclear or nucleolar staining, with little cytoplasmic signal. | Question this as an IHC result: HPA describes tissue staining as cytoplasmic (HPA tissue IHC). ICC-IF also reports nucleoplasm and nucleoli, but marks both locations uncertain; its mitochondrial assignment is supported (HPA subcellular). Check antibody and detection controls before calling the nuclear signal CPT2. |
| Strong signal in adipocytes or lymph-node germinal center cells. | HPA reports CPT2 as Not detected in those specific cell populations (HPA tissue IHC). The discrepancy warrants review for cross-reactivity or endogenous detection activity; it does not, by itself, prove either cause. Compare the same run with a known-positive tissue and appropriate controls. |
| Broad staining over cells and surrounding tissue, with no clear cell pattern. | A uniform haze is difficult to reconcile with HPA's cell-specific positive and Not detected patterns (HPA tissue IHC). In general IHC practice, nonspecific binding or detection background can obscure localization. Inspect a control lacking primary antibody and reassess blocking, washes, and detection. |
| No signal in colon glandular cells or placental syncytiotrophoblasts. | Both are High-staining populations in the HPA tissue record (HPA tissue IHC). If tissue morphology is intact, investigate the IHC workflow and antibody conditions before interpreting the absence as biological. HPA's Enhanced rating does not guarantee a positive result under every laboratory condition (HPA tissue IHC). |
💡Expected CPT2 appearanceCall a result positive when staining is predominantly cytoplasmic in an HPA High cell population, such as colon glandular cells, with a clear cellular pattern; widespread haze or dominant nuclear-only staining needs control review (HPA tissue IHC; HPA subcellular).
| Subcellular location | CPT2 is assigned to the mitochondrial inner membrane, with matrix-facing regions (UniProt P23786 topology). This supports a cytoplasmic IHC interpretation; routine chromogenic resolution cannot identify the membrane itself. |
| Cell population | HPA reports High staining in several glandular populations, kidney collecting ducts, and placental syncytiotrophoblasts, while named adipocytes and lymph-node germinal center cells are Not detected (HPA tissue IHC). Score the identified cells, rather than a whole tissue, against that record. |
| Evidence strength | HPA rates tissue IHC reliability Enhanced and describes medium consistency with RNA expression (HPA tissue IHC). Its antibody list rates HPA028201 and HPA028202 Enhanced for IHC, and HPA028214 Supported for IHC (HPA antibodies). These ratings support comparison with HPA patterns, not automatic validation of another antibody. |
| Processing and isoforms | UniProt annotates a mature chain spanning residues 26–658 and lists zero isoforms for this record (UniProt P23786). Without an antibody epitope in the supplied evidence, these annotations cannot predict whether a particular IHC reagent recognizes the precursor or mature protein. |
| IF/ICC Q&A: should nuclear fluorescence count as the expected result? | HPA ICC-IF lists supported mitochondrial localization, plus uncertain nucleoplasm and nucleoli (HPA subcellular). Treat nuclear fluorescence as a finding requiring controls and context; use the separate IF/ICC guide for method choices. |
| Situation | Likely cause | Next action |
|---|---|---|
| Known-positive tissue has no staining. | A negative colon glandular or kidney collecting-duct result conflicts with HPA High staining (HPA tissue IHC); the cause cannot be assigned from the image alone. | Verify tissue identity and run controls, then review antigen retrieval, antibody conditions, and detection using the validated IHC-P instructions for the chosen reagent. |
| Signal appears chiefly in nuclei. | Tissue IHC is described as cytoplasmic (HPA tissue IHC); ICC-IF nuclear assignments are uncertain (HPA subcellular). | Inspect a control lacking primary antibody and compare a known-positive cell population. Avoid scoring nuclear signal alone as expected CPT2 staining. |
| Unexpectedly strong adipocyte staining. | Adipocytes are Not detected in HPA tissue IHC (HPA tissue IHC); cross-reactivity or background is possible. | Confirm the stained cells are adipocytes, compare an HPA High population in the same run, and check detection controls before assigning specificity. |
| Diffuse brown background obscures cells. | In general chromogenic IHC practice, nonspecific binding or endogenous detection activity may produce background. | Review a control lacking primary antibody; reassess blocking, washes, and the detection system, then judge staining only where cell boundaries and localization remain interpretable. |
| Signal is weaker than expected in brain or thyroid. | HPA lists cerebral-cortex neuronal cells, hippocampal glial cells, and thyroid glandular cells as Low (HPA tissue IHC). | Use an HPA High cell population as the positive comparator before changing conditions. Record the cell population and intensity separately. |
| Two antibodies give different tissue patterns. | HPA reports different IHC validation levels across its listed antibodies (HPA antibodies); those ratings alone do not identify why results diverge. | Compare localization and cell populations with HPA tissue IHC, verify each reagent's IHC-P conditions, and retain controls for both runs. |
Experiment evidence
IHC & IF images showing CPT2 staining
M02112 · IHCIHC analysis of CPT2 using anti-CPT2 antibody (M02112). CPT2 was detected in a paraffin-embedded section of human acinic cell carcinoma of p
M02112 · IHCIHC analysis of CPT2 using anti-CPT2 antibody (M02112). CPT2 was detected in a paraffin-embedded section of human acinic cell carcinoma of p
M02112 · IFImmunofluorescent analysis of MCF-7 cells, using CPT2 Antibody.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000157184-CPT2/tissue/cerebral+cortex#imid_7047568
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000157184-CPT2/tissue/colon#imid_7047486
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000157184-CPT2/tissue/liver#imid_7047495
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000157184-CPT2/tissue/kidney#imid_7047480
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA028214; green = CPT2, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA028214; green = CPT2, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CPT2 IHC & IF
🧪Run kidney first and expect collecting duct cells to stain (HPA: High in kidney collecting ducts); use adipose tissue adipocytes as the negative tissue (HPA: Not detected in adipocytes). Internally negative cells should show counterstain without specific granular cytoplasmic DAB staining, but the supplied kidney HPA row does not identify a cell type that can be designated negative in advance (HPA: High in collecting ducts; UniProt P23786: mitochondrial inner membrane).
Positive control tissue: Adrenal gland (Glandular cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CPT2 in A-431, U-251MG, U2OS, with annotated localisation: Nucleoplasm (uncertain), Mitochondria (supported) (HPA subcellular).
Technical controls: Include no-primary (secondary-only), rabbit IgG isotype controls matched to the primary where possible, and a CPT2 knockout sample or validated peptide-block control (caption: M02112 rabbit primary; standard IHC practice). For HRP/DAB, block endogenous peroxidase; if using avidin-biotin detection, check kidney endogenous biotin background (caption: M02112 HRP/DAB; standard IHC practice).
⚠️Feasibility: A CPT2-specific fixation window or fixation effect is unreported, and the selected M02112 paraffin-section caption does not state the fixative (caption: M02112). Heat retrieval in EDTA at pH 8.0 is a starting condition from that parotid-tissue IHC example, not evidence that kidney staining requires it (caption: M02112). Frozen-section performance is unreported; HPA documents ICC-IF images but does not establish that IF is easier, and kidney endogenous biotin can complicate avidin-biotin detection (HPA: CPT2 subcellular; standard IHC practice).
HPA tissue IHC evidence for CPT2
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium 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 → |
| Colon | Glandular cells | High | Protein (IHC) | HPA → |
| Duodenum | Glandular cells | High | Protein (IHC) | HPA → |
| Gallbladder | Glandular cells | High | Protein (IHC) | HPA → |
| Kidney | Collecting ducts | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Cerebellum | Cells in granular layer | Not detected | Protein (IHC) | HPA → |
| Lymph node | Germinal center cells | Not detected | Protein (IHC) | HPA → |
| Ovary | Ovarian stroma cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced CPT2 IHC Tips
Troubleshoot CPT2 staining by checking retrieval, cellular pattern, controls, and scoring against the documented paraffin-section IHC example and reference localisation data.
Which retrieval conditions should I start with for CPT2 paraffin sections?
Start with heat-mediated retrieval in EDTA at pH 8.0 for CPT2 paraffin sections (datasheet M02112). The documented image used that condition before 10% goat-serum blocking and a 1:50 primary incubation overnight at 4°C (datasheet M02112). If staining is weak, compare retrieval duration on adjacent sections while keeping antibody incubation, detection, and imaging conditions fixed (standard IHC practice). Include a known positive glandular compartment, such as colon glandular cells, and a no-primary control in each comparison (HPA: High in colon glandular cells; standard IHC practice). Excessive retrieval can damage morphology or increase nonspecific staining, so judge signal together with tissue preservation (standard IHC practice).
How should I assess whether fixation caused weak CPT2 staining?
The selected paraffin-section caption does not state a fixative, so CPT2-specific fixation sensitivity is unknown (datasheet M02112). Record the actual fixative and fixation duration for each block before comparing staining across cases (standard IHC practice). If a block stains weakly, process adjacent sections with the documented EDTA pH 8.0 retrieval and a matched positive control from the same staining run (datasheet M02112; standard IHC practice). Compare tissue morphology and control staining before attributing loss of signal to fixation (standard IHC practice). Neither the reported tissue staining pattern nor CPT2 topology establishes how a particular fixative affects this epitope (HPA tissue IHC; UniProt P23786 topology).
What cellular pattern supports specific CPT2 staining in chromogenic IHC?
Expect a cytoplasmic signal compatible with mitochondria, because CPT2 is associated with the mitochondrial inner membrane and its annotated regions face the matrix (UniProt P23786 topology). Chromogenic tissue IHC may show a broad cytoplasmic pattern rather than resolve individual mitochondria (HPA: cytoplasmic expression in most tissues; standard IHC practice). Compare intensity within defined cell populations: glandular cells in colon and collecting ducts in kidney are reported as High (HPA tissue IHC). Predominantly nuclear DAB staining needs independent validation, since the reported nucleoplasmic location is uncertain whereas mitochondrial localisation is supported (HPA subcellular). Check a no-primary section and inspect cell borders and tissue edges before calling an unusual compartment positive (standard IHC practice).
How do processing and epitope position affect CPT2 IHC interpretation?
CPT2 is listed as a 658-amino-acid precursor with a processed chain spanning residues 26–658, and no isoforms are annotated (UniProt P23786 processing; UniProt P23786 isoforms). Its annotated matrix-facing regions are residues 26–178 and 209–658, with no transmembrane segment annotated (UniProt P23786 topology). Because the selected caption gives no epitope coordinates, do not assume that staining reports a particular terminus or processing state (datasheet M02112). Acetylation and succinylation are annotated at several residues, but their effects on this antibody's binding are not established here (UniProt P23786 modified residues). If staining changes between specimens, check retrieval and controls before assigning the difference to processing or modification (standard IHC practice).
How can IF help resolve an ambiguous CPT2 IHC pattern?
Use the separate IF/ICC workflow to test whether CPT2 signal overlaps a mitochondrial marker and a marker identifying the expected cell population (UniProt P23786 localisation; HPA tissue IHC; standard IF practice). For example, a glandular-cell marker can help interpret a region selected because glandular cells stain High in colon IHC (HPA tissue IHC). Choose a fluorophore channel with low tissue autofluorescence and include single-channel controls before interpreting overlap (standard IF practice). CPT2's annotated regions face the mitochondrial matrix, so permeabilisation must provide access to a matrix-facing epitope if that is where this antibody binds (UniProt P23786 topology; standard IF practice). The epitope position and IF-specific conditions are not supplied by the selected IHC caption (datasheet M02112).
What should I check when CPT2 DAB staining looks diffuse?
First inspect the no-primary control, tissue edges, and damaged areas to distinguish background from cell-associated signal (standard IHC practice). The selected image used 10% goat-serum blocking, a 1:50 rabbit primary overnight at 4°C, a peroxidase-conjugated secondary, and DAB development (datasheet M02112). Block endogenous peroxidase before HRP detection, and compare secondary-only staining when background persists (standard chromogenic IHC practice). Check whether extended DAB development or inadequate washing produces diffuse colour across compartments that should differ (standard IHC practice). A convincing pattern should remain interpretable in cytoplasm and agree with the tested positive-cell control (HPA: cytoplasmic expression in most tissues; standard IHC practice).
How should I score CPT2 staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and cytoplasmic scoring region before reviewing case labels (standard IHC practice; HPA: cytoplasmic expression in most tissues). Record either the percentage of positive cells with intensity categories for an H-score, or positive-cell density per mm² within a fixed tissue compartment (standard IHC practice). Keep retrieval, antibody dilution, DAB development, illumination, and threshold settings matched across the comparison (standard IHC practice). Normalise to viable cells or evaluable compartment area rather than total section area when tissue composition differs (standard IHC practice). Report control performance and the cell type scored, because HPA records both High and Not detected populations across tissues (HPA tissue IHC).
How can I distinguish genuine CPT2 signal from staining artefact?
A credible signal is cell-associated and mainly cytoplasmic, consistent with CPT2's mitochondrial inner-membrane assignment and the reported tissue IHC pattern (UniProt P23786 topology; HPA tissue IHC). Compare positive compartments, such as kidney collecting ducts, with a reported Not detected population, such as lymph-node germinal-center cells, using the same scoring rules (HPA tissue IHC; standard IHC practice). Treat isolated nuclear staining cautiously because mitochondrial localisation is supported while nucleoplasmic localisation is uncertain (HPA subcellular). Exclude section-edge accentuation, necrotic areas, and staining present in no-primary or peroxidase controls before assigning positivity (standard chromogenic IHC practice). HPA reports only medium consistency between antibody staining and RNA expression, so corroborate unexpected biology with an independent assay (HPA reliability).
Boster reagents
Best CPT2 / Carnitine O-palmitoyltransferase 2, mitochondrial IHC Antibodies
CPT2 IHC is shown in human paraffin sections and IF in MCF-7 cells (M02112 image captions); both antibodies list human, mouse and rat reactivity (catalog reactivity).
Real IHC data
Anti-CPT2 Rabbit Monoclonal Antibody
Cat # M02112
M02112 lists IHC and ICC/IF, with IHC images from human acinic cell carcinoma of parotid and cervical cancer paraffin sections and an IF image from MCF-7 cells (catalog applications; M02112 image captions). A02112-1 lists IHC for human paraffin sections at 2–5 μg/ml and human, mouse and rat reactivity; no IHC or IF image is supplied (catalog applications, dilution and image alts).
Which to pick: For tissue IHC, choose monoclonal M02112: its paraffin-section captions document EDTA retrieval at pH 8.0 and primary antibody at 1:50; the fixative is unreported (catalog clone; M02112 IHC captions). For IF/ICC, choose M02112 because ICC/IF is listed and an MCF-7 IF image is supplied (catalog applications; M02112 IF caption). For work across species, both SKUs list human, mouse and rat reactivity, but the supplied M02112 tissue images show human samples and A02112-1 specifies human IHC; verify staining in mouse or rat tissue (catalog reactivity and dilution; M02112 IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P23786 (CPT2_HUMAN, Carnitine O-palmitoyltransferase 2, mitochondrial).
- Human Protein Atlas. CPT2 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. CPT2 subcellular location (ICC-IF): Mainly localized to the nucleoplasm and mitochondria. In addition localized to the nucleoli..
- Human Protein Atlas. CPT2 antibody validation summary (3 antibodies).
- Proteomics Analysis Provides Insights into the Role of Lipid Metabolism in T2DM-Related Sarcopenia. ACS omega 2024 — PMC11308078.
- Identification of a lipid metabolism-related gene for cancer immunotherapy. Frontiers in pharmacology 2023 — PMC10213444.
- Schisandrin B Attenuates Renal Fibrotic Remodeling in Association with Restoration of a PPARα-Related Tubular Fatty-Acid Oxidation Program. Biomedicines 2026 — PMC13297011.
- SIRT3 mediates CPT2 delactylation to enhance mitochondrial function and proliferation in goat granulosa cells. Journal of animal science and biotechnology 2025 — PMC12269156.
- PubMed PMID:1988962 — UniProt-cited evidence.
- PubMed PMID:1961767 — UniProt-cited evidence.
- PubMed PMID:7711730 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CPT2 (Carnitine O-palmitoyltransferase 2, mitochondrial). Expected localisation Cytoplasmic tissue staining (HPA tissue IHC); mitochondrial inner membrane (UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet M02112). Validated IHC antibody: M02112 at 1:50 (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human acinic cell carcinoma of parotid tissue; fixative not specified (datasheet M02112); 2. Fixation: Image fixative and duration unreported (datasheet M02112); 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 M02112); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet M02112); 8. Primary antibody: Rabbit monoclonal (clone FGB-3) anti-CPT2, 1:50 (datasheet M02112); 9. Primary incubation: Overnight at 4 °C (datasheet M02112). Watch for: Fixation: Keep paraffin tissue fixation consistent (standard IHC practice; not target-specific); Caveat: Adipocytes have no detected staining (HPA tissue IHC); Isoform / epitope: No isoforms annotated; mature chain spans aa 26–658 (UniProt); Regulation: Liver-enhanced RNA; IHC effect unknown (HPA RNA). Evidence: UniProt P23786, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the nucleoplasm and mitochondria. In addition…, Datasheet M02112, PMC11308078, PMC13297011. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CPT2/immunohistochemistry-ihc-guide.