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CYP11A1 / Cholesterol side-chain cleavage enzyme, mitochondrial · IHC design guide
Design Immunohistochemistry for CYP11A1
Plan chromogenic IHC for CYP11A1 in paraffin sections using the catalog antibody at 0.5–1 μg/ml (datasheet). Compare granular cytoplasmic staining in adrenal zona fasciculata cells, placental cytotrophoblasts and testicular Leydig cells (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CYP11A1 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 | Granular cytoplasm in zona fasciculata, cytotrophoblasts and Leydig cells (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Adrenal gland+2 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
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 is cell restricted within positive tissues (HPA tissue IHC) | |
| Regulation | Adrenal gland enriched (HPA tissue IHC) | |
| Isoform / epitope | 2 isoforms; epitope impact is unknown (UniProt) |
Section 1
Recommended CYP11A1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by four published CYP11A1 chromogenic IHC methods for canine adrenal tissue and rat adrenal or testis sections (PMC11586580; PMC12375238; PMC7541273; PMC8072358).
| Sample | Tissue sections; selected-image fixative not specified (standard IHC workflow) |
| Fixation | Image fixative and duration unreported (datasheet PA1698); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in citrate buffer, pH 6.0, 20 min at 95–98 °C (standard rule: cytoplasmic / membrane antigen) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Rabbit anti-CYP11A1, 0.5-1μg/ml (datasheet PA1698) |
| Primary incubation | Overnight at 4 °C (standard) |
| Detection | HRP-polymer secondary, DAB chromogen 5–10 min (standard) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | CYP11A1-positive staining in cells in zona fasciculata of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Granular cytoplasmic expression, most abundant in adrenal gland, placenta and testis. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page antigen retrieval); compare staining with tissue controls (PMC11586580).
Section 2
What Is the Expected CYP11A1 Staining Pattern?
CYP11A1 is on the matrix side of the mitochondrial inner membrane and has no annotated transmembrane segment (UniProt P05108 topology). In paraffin-section IHC, expect granular cytoplasmic staining, with high staining in adrenal zona fasciculata cells, placental cytotrophoblasts and testicular Leydig cells (HPA: Enhanced tissue IHC; High in each listed cell type). HPA’s Enhanced rating reflects consistency between antibody staining and RNA expression data (HPA: reliability description).
| Granular cytoplasmic staining in the expected cell populations. | This matches the reported tissue pattern (HPA: granular cytoplasmic expression; High in zona fasciculata cells, cytotrophoblasts and Leydig cells). Score the named cells rather than treating an entire tissue as uniformly positive (HPA: cell-specific IHC levels). |
| Predominantly nuclear staining or a crisp cell-surface outline. | These compartments do not match the mitochondrial inner-membrane location or HPA’s granular cytoplasmic pattern (UniProt P05108 topology; HPA: tissue IHC profile). Treat the result as suspect; compare it with a known-positive section and a no-primary control before assigning specificity (general IHC practice). |
| Strong staining in cells reported as negative, such as adipocytes in adipose tissue. | HPA reports CYP11A1 as not detected in those adipocytes (HPA: adipose tissue, adipocytes). Consider antibody cross-reactivity or endogenous detection activity, especially if a no-primary control also develops signal (general IHC practice). A negative HPA entry does not establish that every cell in that tissue must be unstained (HPA: cell-specific IHC entry). |
| Diffuse color across positive and negative regions without a granular cellular pattern. | This is difficult to interpret as CYP11A1 because the reference pattern is granular and cell-specific (HPA: tissue IHC profile and cell-level results). Inspect the no-primary control, wash steps and detection background before scoring cells (general IHC practice). |
| No staining in adrenal zona fasciculata cells, placental cytotrophoblasts or testicular Leydig cells. | A blank result in a suitable known-positive section conflicts with the reported high staining in those cells (HPA: High in each listed cell type). Check section quality, retrieval and detection controls before calling an experimental specimen negative (general IHC practice); no CYP11A1-specific retrieval condition is supplied. |
💡Expected CYP11A1 appearanceCall a result concordant when high, granular cytoplasmic staining occurs in the named positive cells (HPA: tissue IHC); dominant nuclear, surface or widespread negative-cell staining is suspect against the mitochondrial location and cell-specific reference pattern (UniProt P05108 topology; HPA: tissue IHC).
| Subcellular location and processing | CYP11A1 resides on the matrix side of the mitochondrial inner membrane; UniProt annotates a mature chain spanning residues 40–521 and no transmembrane segment (UniProt P05108 topology and processing). Use these annotations to assess localisation, without inferring an antibody epitope or a retrieval setting. |
| Isoforms | UniProt lists 2 isoforms (UniProt P05108 isoforms). No isoform-specific staining pattern or antibody epitope is supplied, so the IHC pattern cannot identify which isoform produced the signal. |
| Tissue-reference confidence | HPA rates the tissue IHC profile Enhanced and lists one antibody, HPA016436, with Enhanced IHC validation (HPA: tissue reliability; antibody record). This supports comparison with the reported cells; it does not validate every new specimen or detection setup. |
| IF/ICC: is a cellular pattern confirmed? | HPA provides no main ICC-IF location or cell-line images for CYP11A1 (HPA: subcellular record). A mitochondrial pattern is expected from UniProt location, but that record supplies no observed IF/ICC staining pattern (UniProt P05108 topology; HPA: subcellular record). |
| Situation | Likely cause | Next action |
|---|---|---|
| Known-positive cells are blank. | The run may have failed, or section processing may have reduced detectable signal (general IHC practice). HPA does not report CYP11A1 fixation sensitivity or a retrieval requirement. | Run a known-positive section alongside the specimen; verify retrieval, antibody incubation and detection with the assay controls (general IHC practice). Do not infer a CYP11A1-specific fixation effect. |
| Signal is mainly nuclear or at the cell border. | That pattern conflicts with the annotated mitochondrial location and granular cytoplasmic IHC profile (UniProt P05108 topology; HPA: tissue IHC). | Compare a known-positive section and no-primary control; reassess localisation only if those controls support specific staining (general IHC practice). |
| Adipocytes stain strongly in an adipose-tissue section. | These cells are listed as not detected (HPA: adipose tissue, adipocytes); cross-reactivity or detection background is possible (general IHC practice). | Check the no-primary control and compare cellular morphology with the HPA cell-level reference before scoring the stain (general IHC practice; HPA: adipose tissue entry). |
| Color appears throughout the section, including spaces without cells. | Widespread chromogen background can obscure the reported granular cellular pattern (general IHC practice; HPA: tissue IHC profile). | Check no-primary background, blocking and washes; then judge staining in identifiable cells rather than diffuse color (general IHC practice). |
| A no-primary section develops chromogen. | The primary antibody cannot explain signal in that control; endogenous detection activity or reagent background is possible (general IHC practice). | Address the detection system’s endogenous activity and background according to its controls, then repeat the comparison with a known-positive section (general IHC practice). |
| An IF/ICC image shows diffuse cytoplasmic fluorescence. | HPA supplies no ICC-IF images or confirmed main location for comparison (HPA: subcellular record); UniProt places CYP11A1 at mitochondria (UniProt P05108 topology). | Treat the image as unconfirmed and assess antibody and background controls in the separate IF/ICC workflow (general IF practice); do not cite HPA tissue IHC as IF validation. |
Experiment evidence
IHC & IF images showing CYP11A1 staining
PA1698 · IHCAnti-CYP11A1 antibody, PA1698, IHC(P) IHC(P): Human Placenta Tissue
PA1698 · IHCAnti-CYP11A1 antibody, PA1698, IHC(F) IHC(F): Human Placenta Tissue
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000140459-CYP11A1/tissue/cerebral+cortex#imid_17602507
HPA · Adrenal glandHuman Protein Atlas IHC, Adrenal gland. Source: https://www.proteinatlas.org/ENSG00000140459-CYP11A1/tissue/adrenal+gland#imid_121
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000140459-CYP11A1/tissue/colon#imid_17602433
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000140459-CYP11A1/tissue/liver#imid_17602434
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CYP11A1 IHC & IF
🧪Run placenta first: cytotrophoblasts should stain strongly (HPA: High in placental cytotrophoblasts). Use bronchus respiratory epithelial cells as the negative tissue (HPA: Not detected); other cells on the positive slide should show only background staining unless independently validated as CYP11A1 positive (HPA: High designation applies to cytotrophoblasts).
Positive control tissue: Adrenal gland (Cells in zona fasciculata, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for CYP11A1; derive a cell-line control from the positive tissue's cell type (Cells in zona fasciculata) and confirm it by RNA or western blot first.
Technical controls: Include a no-primary, secondary-only control and an isotype control matched to the primary antibody’s host species and immunoglobulin class; use CYP11A1 knockout material, if available, as a biological negative (standard IHC practice). For placental chromogenic IHC, check endogenous peroxidase and, if using biotin-based detection, endogenous biotin; for IF, assess tissue autofluorescence (standard IHC/IF practice).
⚠️Feasibility: A target-specific fixation window and retrieval dependency are unreported in the supplied evidence; the selected PA1698 paraffin-section placenta caption does not state a fixative (PA1698 caption). The caption supports placental IHC-P use, but provides no basis to conclude that frozen sections or IF are easier (PA1698 caption). Placental endogenous peroxidase can complicate chromogenic interpretation, so assess it with the detection controls (standard IHC practice).
HPA tissue IHC evidence for CYP11A1
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 | Cells in zona fasciculata | High | Protein (IHC) | HPA → |
| Placenta | Cytotrophoblasts | High | Protein (IHC) | HPA → |
| Testis | Leydig cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced CYP11A1 IHC Tips
Troubleshoot CYP11A1 chromogenic IHC in paraffin sections using its expected mitochondrial pattern and documented tissue controls (UniProt P05108; HPA tissue IHC).
How should I adjust retrieval when CYP11A1 staining is weak?
Start with citrate buffer at pH 6.0, heated to 95–98 °C for 20 min (page retrieval rule: cytoplasmic/membrane antigen). Cool the sections in buffer for about 20 min, then apply the same staining conditions to a positive control and the test sections (standard IHC practice). CYP11A1 faces the mitochondrial matrix, and tissue staining is described as granular cytoplasmic (UniProt P05108 topology; HPA tissue IHC). If staining remains weak, test a higher-pH retrieval buffer as a fallback on adjacent sections (standard IHC practice). Compare signal with tissue preservation and background before adopting the fallback (standard IHC practice).
Could fixation explain weak CYP11A1 staining in paraffin sections?
Target-specific fixation sensitivity is unknown from the supplied evidence; the PA1698 tissue-IHC caption identifies a paraffin-section image but does not state its fixative (caption PA1698). Record fixative, duration, and processing history for each specimen before changing the staining protocol (standard IHC practice). If material permits, compare sections fixed for 6 and 24 h in 10% neutral buffered formalin under identical retrieval and detection conditions (standard IHC practice). Assess both staining intensity and tissue morphology, because a stronger signal alone does not establish better preservation (standard IHC practice). Do not infer fixation tolerance from tissue expression patterns or mitochondrial topology (HPA tissue IHC; UniProt P05108 topology).
What staining pattern should count as CYP11A1 localisation?
Look for granular cytoplasmic staining in the expected cells; tissue IHC reports that pattern, while UniProt places CYP11A1 on the matrix side of the mitochondrial inner membrane (HPA tissue IHC; UniProt P05108 topology). Evaluate the granules at matched magnification and counterstain across test and control sections (standard IHC practice). Adrenal zona fasciculata cells, placental cytotrophoblasts, and testicular Leydig cells are documented high-expression controls (HPA tissue IHC). Diffuse nuclear staining alone does not match the reported localisation and should prompt a review of specificity and detection background (HPA tissue IHC; UniProt P05108 topology). Do not expect chromogenic IHC to resolve individual mitochondrial membranes (standard IHC practice).
Can an unknown antibody epitope complicate CYP11A1 IHC interpretation?
Yes: CYP11A1 has 2 annotated isoforms, while the supplied PA1698 caption does not identify the antibody epitope (UniProt P05108 isoforms; caption PA1698). The annotated mature chain spans residues 40–521, and no transmembrane segment or glycosylation site is annotated (UniProt P05108 processing, topology, glycosylation). Those annotations do not establish which isoforms or processed forms the antibody recognizes (UniProt P05108; caption PA1698). When specificity is uncertain, compare positive and negative tissue controls and, if available, an independently characterized antibody targeting a distinct epitope (HPA tissue IHC; standard IHC practice). Keep retrieval and chromogenic exposure matched across adjacent sections so epitope comparisons remain interpretable (standard IHC practice).
How can IF help check the cellular source of CYP11A1 staining?
Use IF as a separate validation experiment: the supplied PA1698 evidence is tissue IHC, and the HPA subcellular payload lists no ICC/IF images (caption PA1698; HPA subcellular). Multiplex CYP11A1 with a validated cytotrophoblast lineage marker when examining placenta, where cytotrophoblasts are reported high (HPA tissue IHC; standard IF practice). Choose a far-red channel and inspect an unstained section to distinguish fluorophore signal from tissue autofluorescence (standard IF practice). Because CYP11A1 faces the mitochondrial matrix, test permeabilisation if the antibody recognizes that face; its epitope is unspecified here (UniProt P05108 topology; caption PA1698). Compare about 5 min of mild detergent treatment with a matched untreated section, checking morphology and background (standard IF practice).
How do I reduce diffuse brown staining without losing CYP11A1 signal?
First compare the stained section with a no-primary control and a documented low-expression cell population (standard IHC practice; HPA tissue IHC). Use a peroxidase block, such as 3% hydrogen peroxide for about 10 min, before a DAB detection workflow (standard chromogenic IHC practice). Apply a protein block, wash consistently, and titrate primary antibody concentration and incubation time while holding retrieval constant (standard IHC practice). Adipocytes in adipose tissue and glandular cells in appendix are reported as not detected and can help reveal nonspecific staining (HPA tissue IHC). Judge improvement by retained granular cytoplasmic signal in a positive control alongside reduced no-primary staining (HPA tissue IHC; standard IHC practice).
How should I score heterogeneous CYP11A1 staining across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and viable tissue area before scoring, using the same rules for every section (standard IHC practice). For cell-based scoring, record the percentage of positive cells and an intensity grade of 0–3; their weighted sum gives an H-score of 0–300 (standard IHC practice). Alternatively, report positive-cell density per mm² of viable tissue when cell counts vary substantially (standard IHC practice). Normalize comparisons to the same cell type and sampled area, and document counterstain and exposure settings (standard IHC practice). In placenta, score cytotrophoblasts separately from surrounding cells because their reported CYP11A1 expression is high (HPA tissue IHC).
What separates genuine CYP11A1 staining from a chromogenic artefact?
A credible result combines granular cytoplasmic staining with the expected cell population, consistent with mitochondrial localisation and tissue IHC (UniProt P05108 topology; HPA tissue IHC). Compare high-expression adrenal zona fasciculata cells or placental cytotrophoblasts with a documented not-detected population, such as adipose adipocytes (HPA tissue IHC). Treat predominantly nuclear signal, staining limited to section edges, or deposits over necrotic areas as reasons to investigate artefact (UniProt P05108 topology; standard IHC practice). Run a no-primary control and check the peroxidase block when brown deposits could reflect endogenous enzyme activity (standard chromogenic IHC practice). Interpret differences only after checking comparable retrieval, counterstain, and viable tissue preservation (standard IHC practice).
Boster reagents
Best CYP11A1 / Cholesterol side-chain cleavage enzyme, mitochondrial IHC Antibodies
PA1698 has a human placenta paraffin-section IHC image (PA1698 IHC(P) caption). No IF/ICC image is supplied (catalog IF image list).
Real IHC data
Anti-CYP11A1 Antibody ®
Cat # PA1698
PA1698 is listed for human IHC (catalog applications; reactivity). Its IHC(P) image shows human placenta tissue (PA1698 IHC(P) caption).
Which to pick: Choose PA1698 for human paraffin-section tissue IHC based on its own placenta image (PA1698 IHC(P) caption); the listed IHC concentration is 0.5–1 μg/ml (catalog dilution). There is no validated IF/ICC or cross-species option in the supplied catalog (catalog applications: IHC, WB; reactivity: Human; IF image list: empty). PA1698 has a rabbit host and unreported clonality (catalog host; clone), while its IHC(P) caption does not report the fixative (PA1698 IHC(P) caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P05108 (CP11A_HUMAN, Cholesterol side-chain cleavage enzyme, mitochondrial).
- Human Protein Atlas. CYP11A1 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. CYP11A1 subcellular location (ICC-IF): Highest expression in HEL: 81.9 nTPM.
- Human Protein Atlas. CYP11A1 antibody validation summary (1 antibodies).
- Immunohistochemical expression of CYP11A1, CYP11B, CYP17, and HSD3B2 in functional and nonfunctional canine adrenocortical tumors. Journal of veterinary internal medicine 2024 — PMC11586580.
- Prenatal linuron exposure disrupts adrenal steroidogenesis and induces adrenal insufficiency in male rat offspring. Current research in toxicology 2025 — PMC12375238.
- Monocyte Chemoattractant Protein-1 stimulates the differentiation of rat stem and progenitor Leydig cells during regeneration. BMC developmental biology 2020 — PMC7541273.
- The Production of Testosterone and Gene Expression in Neonatal Testes of Rats Exposed to Diisoheptyl Phthalate During Pregnancy is Inhibited. Frontiers in pharmacology 2021 — PMC8072358.
- PubMed PMID:3024157 — UniProt-cited evidence.
- PubMed PMID:3038854 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CYP11A1 (Cholesterol side-chain cleavage enzyme, mitochondrial). Expected localisation Granular cytoplasm (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: PA1698 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Cells in zona fasciculata); negative Adipose tissue. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Tissue sections; selected-image fixative not specified (standard IHC workflow); 2. Fixation: Image fixative and duration unreported (datasheet PA1698); 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-induced epitope retrieval in citrate buffer, pH 6.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-CYP11A1, 0.5-1μg/ml (datasheet PA1698); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Staining is cell restricted within positive tissues (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope impact is unknown (UniProt); Regulation: Adrenal gland enriched (HPA tissue IHC). Evidence: UniProt P05108, HPA tissue IHC · Enhanced, HPA cell-line RNA · Highest expression in HEL: 81.9 nTPM, Datasheet PA1698, PMC11586580, PMC12375238. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CYP11A1/immunohistochemistry-ihc-guide.