CYP1A1 / Cytochrome P450 1A1 · IHC design guide

Design Immunohistochemistry for CYP1A1

Plan CYP1A1 staining in paraffin sections using the catalog antibody’s IHC range of 0.5–1 μg/mL (datasheet PB9544). Compare cytoplasmic staining with tissue controls while accounting for the uncertain HPA staining profile (HPA tissue IHC).

Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
Immunohistochemistry protocol sheet for CYP1A1 (IHC for CYP1A1): expected localisation Cytoplasm observed (HPA tissue IHC); ER and inner mitochondrial membrane annotated (UniProt), antibody PB9544, validated IHC image, and IHC protocol steps
Printable CYP1A1 IHC protocol sheet — expected localisation Cytoplasm observed (HPA tissue IHC); ER and inner mitochondrial membrane annotated (UniProt), antibody PB9544, controls and protocol steps. Open the full CYP1A1 IHC guide →

CYP1A1 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 Cytoplasm observed (HPA tissue IHC); ER and inner mitochondrial membrane annotated (UniProt)
Staining pattern General cytoplasmic staining, including glandular cells (HPA tissue IHC)
Antigen retrieval Citrate pH 6 HIER, heat-mediated (datasheet PB9544)
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 fixation consistent (standard IHC practice; not target-specific); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image PB9544)
Caveat Very low agreement between staining and RNA data (HPA tissue IHC)
Regulation Expression varies by tissue (UniProt)
Isoform / epitope Three isoforms; antibody epitope coverage is unknown (UniProt)
Section 1

Recommended CYP1A1 IHC & IF Protocols

The catalog antibody has its own IHC-P protocol (datasheet PB9544). The four published protocols below provide tissue-specific methods for comparison (PMC1310924; PMC11544920; PMC4201582; PMC8082009).

Recommended immunohistochemistry (IHC-P) protocol parameters
SampleParaffin-embedded Mouse Kidney tissue; fixative not specified (datasheet PB9544)
FixationImage fixative and duration unreported (datasheet PB9544); verify before use.
Sectioning4–5 µm sections on charged slides (standard)
DeparaffinisationXylene, graded ethanol series to water (standard)
Antigen retrievalHeat retrieval: Citrate pH 6, 20 min (datasheet PB9544)
Peroxidase block3% H2O2, 10 min, room temperature (standard)
Blocking10% goat serum (datasheet PB9544)
Primary antibodyRabbit anti-CYP1A1, 0.5-1μg/ml (datasheet PB9544)
Primary incubationOvernight at 4 °C (datasheet PB9544)
DetectionStreptavidin-biotin complex (SABC), DAB chromogen (datasheet PB9544)
CounterstainHematoxylin, blue, dehydrate and mount (standard)
Expected resultCYP1A1-positive staining in glandular cells of adrenal gland (HPA tissue IHC: Medium). HPA tissue profile: General cytoplasmic expression. No signal in the no-primary control.
💡Decision noteStart with heat-mediated citrate retrieval at pH 6 for the catalog antibody (datasheet PB9544); a published fish-tissue protocol also specifies this buffer (PMC11544920).
Section 2

What Is the Expected CYP1A1 Staining Pattern?

CYP1A1 is annotated in the endoplasmic reticulum and microsome membranes, mitochondrial inner membrane, and cytoplasm, with no annotated transmembrane segment (UniProt P04798 topology). On paraffin sections, look for cytoplasmic staining in bronchial respiratory epithelial cells or selected glandular cells reported at medium intensity (HPA tissue IHC). Treat that pattern as provisional: tissue staining has Uncertain reliability, and the listed antibody’s IHC validation is Uncertain (HPA tissue IHC; HPA CAB018654).

What am I looking at on my slide?
Cytoplasmic staining in bronchial respiratory epithelial cells or glandular cells.This fits the reported general cytoplasmic profile; HPA records medium staining in bronchus and in selected glandular tissues, including colon and duodenum (HPA tissue IHC). The expected compartment also fits CYP1A1’s cytoplasmic and membrane annotations (UniProt P04798 subcellular location). Judge cell identity and distribution alongside intensity, because HPA rates its tissue pattern Uncertain (HPA tissue IHC).
Predominantly nuclear staining with little cytoplasmic signal.A nuclear-only pattern does not match the supplied CYP1A1 locations or HPA’s general cytoplasmic profile (UniProt P04798 subcellular location; HPA tissue IHC). Treat it as suspect and compare the negative reagent control and another tissue section before assigning it to CYP1A1 (general IHC practice). The available records do not establish a diagnostic nuclear staining pattern.
Strong staining in adipocytes, skeletal myocytes, or smooth muscle cells.Those cell types are listed as Not detected in the supplied tissue observations (HPA tissue IHC). Reproducible staining there warrants checking cell identification, cross-reactivity, and endogenous detection activity with appropriate controls (general IHC practice). A Not detected entry is an observation under HPA’s conditions, not proof that every specimen or biological state must be negative (HPA tissue IHC).
Diffuse chromogen across tissue and spaces between cells.Widespread, cell-independent deposit obscures the cytoplasmic pattern used for interpretation (HPA tissue IHC; general IHC practice). Check the negative reagent control, reagent carryover, blocking, and wash quality (general IHC practice). Background alone cannot establish CYP1A1 expression, especially while the tissue pattern and the listed antibody’s IHC result remain Uncertain (HPA tissue IHC; HPA CAB018654).
No visible staining in a bronchus section expected to show signal.HPA reports medium staining in bronchial respiratory epithelial cells, making bronchus a useful comparison specimen, though not a guaranteed positive control (HPA tissue IHC). Confirm that recognizable epithelium is present, then review the catalog antibody’s stated IHC-P conditions and the detection controls (general IHC practice). HPA’s Uncertain reliability prevents calling a negative section a technical failure by itself (HPA tissue IHC).
💡Expected CYP1A1 appearanceCall a section provisionally positive when bronchial respiratory epithelial cells or HPA-listed glandular cells show discernible cytoplasmic staining around the reported medium level; predominantly nuclear, diffuse cell-independent, or unexpectedly strong staining in HPA Not detected cell types needs control-based review (HPA tissue IHC; UniProt P04798 subcellular location; general IHC practice).
How each factor affects the staining
Compartment and topologyCYP1A1 is annotated at endoplasmic reticulum and microsome membranes, mitochondrial inner membrane, and cytoplasm, without an annotated transmembrane segment (UniProt P04798 topology). Paraffin IHC may read these closely spaced structures as cytoplasmic staining; a chromogenic pattern alone does not resolve the organelle (general IHC practice).
Choice of comparison tissueHPA reports medium staining in bronchial respiratory epithelial cells and several glandular cell populations, while adipocytes and skeletal myocytes are Not detected (HPA tissue IHC). These are practical comparison patterns, with limited certainty because antibody staining and RNA expression show very low consistency pending external verification (HPA tissue IHC).
Isoforms and epitope coverageThree isoforms are listed, but the supplied record does not map the antibody epitope or establish which isoforms it detects (UniProt P04798 isoforms; HPA CAB018654). Interpret staining as antibody-reactive CYP1A1 signal rather than an isoform assignment; verify epitope coverage from antibody documentation if isoform discrimination matters (general IHC practice).
Detection chemistryEndogenous activity or nonspecific reagent binding can produce chromogen independently of primary-antibody binding (general IHC practice). Use suitable negative reagent and detection controls when staining appears in unexpected cells or across tissue (general IHC practice). This is a general workflow consideration; the supplied sources report no CYP1A1-specific endogenous detection effect.
IF/ICC Q&A: What localisation can guide IF review?UniProt lists cytoplasm and several membranes, while HPA’s ICC-IF summary says Membrane but supplies no main location or cell-line images (UniProt P04798 subcellular location; HPA subcellular). Review IF localisation cautiously; the supplied ICC-IF record cannot validate a detailed organelle pattern or an IF/ICC protocol (HPA subcellular).
Why is my staining missing, weak or wrong?
SituationLikely causeNext action
Predominantly nuclear chromogen.The compartment differs from the reported cytoplasmic profile and annotated locations (HPA tissue IHC; UniProt P04798 subcellular location).Check the negative reagent control, section quality, and cellular landmarks; repeat interpretation against a section with recognizable cytoplasm (general IHC practice).
Diffuse staining hides cell boundaries.Background from detection reagents, incomplete blocking, or inadequate washing is possible (general IHC practice).Compare a negative reagent control, review blocking and wash steps, and score only discernible cellular staining (general IHC practice).
Unexpected staining in adipocytes or myocytes.These cell types are reported Not detected, so cross-reactivity or endogenous detection activity needs consideration (HPA tissue IHC; general IHC practice).Verify cell identity and compare primary-omission and detection controls before attributing the signal to CYP1A1 (general IHC practice).
Bronchial epithelium appears negative.HPA reports medium respiratory epithelial staining, but its tissue result has Uncertain reliability (HPA tissue IHC).Confirm epithelium is present; check the catalog antibody’s IHC-P instructions, controls, and detection sequence before changing interpretation (general IHC practice).
Patchy staining across a glandular section.Differences in represented cell populations or section quality may affect the apparent pattern (general IHC practice); HPA reports selected glandular cells at medium intensity (HPA tissue IHC).Identify glandular cells on the counterstain, compare intact areas, and document the fraction and location of positive cells (general IHC practice).
A sharp organelle-level claim is needed from chromogenic IHC.The annotated membrane locations are finer than a routine chromogenic cytoplasmic pattern can reliably distinguish (UniProt P04798 subcellular location; general IHC practice).Report cytoplasmic staining at the resolution observed; seek separately validated localisation evidence before naming a specific organelle (general IHC practice).

Sample controls for CYP1A1 IHC & IF

🧪Run bronchus first and look for staining in respiratory epithelial cells (HPA: Medium in bronchus respiratory epithelial cells). Use skeletal muscle myocytes as the negative tissue (HPA: Not detected in skeletal muscle myocytes); on the bronchus slide, compare staining with adjacent cells outside the respiratory epithelium, treating them as background comparators rather than confirmed CYP1A1-negative cells (HPA: Medium in bronchus respiratory epithelial cells).
Positive control tissue: Adrenal gland (Glandular cells, HPA Medium)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for CYP1A1; derive a cell-line control from the positive tissue's cell type (Glandular cells) and confirm it by RNA or western blot first.
Technical controls: Include a no-primary, secondary-only slide and a host- and clonality-matched rabbit IgG isotype control (PB9544 caption: rabbit primary antibody). Use CYP1A1-knockout tissue as a biological negative when available, and block endogenous peroxidase and assess endogenous biotin before SABC/DAB detection, particularly in any inflammatory cells on the bronchus slide (PB9544 caption: biotinylated secondary, SABC and DAB).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported in the supplied evidence, and the selected PB9544 caption does not state a fixative (PB9544 caption: fixative unreported). The caption reports heat retrieval in citrate buffer at pH 6 for 20 minutes in a paraffin-embedded mouse kidney section; whether bronchus requires the same retrieval is unreported (PB9544 caption). The supplied evidence does not establish that frozen sections or IF are easier; for bronchus IHC, watch for endogenous peroxidase or biotin signal when interpreting SABC/DAB staining (PB9544 caption: SABC/DAB detection).

HPA tissue IHC evidence for CYP1A1

Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Uncertain — Very low consistency between antibody staining and RNA expression data. Pending external verification.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.

Positive expression · recommended positive controls

TissueCell typeLevelEvidenceSource
Adrenal gland Glandular cells Medium Protein (IHC) HPA →
Appendix Glandular cells Medium Protein (IHC) HPA →
Bronchus Respiratory epithelial cells Medium Protein (IHC) HPA →
Cerebellum Purkinje cells Medium Protein (IHC) HPA →
Colon Glandular cells Medium Protein (IHC) HPA →

Undetected expression · recommended negative controls

TissueCell typeLevelEvidenceSource
Adipose tissue Adipocytes Not detected Protein (IHC) HPA →
Bone marrow Hematopoietic cells Not detected Protein (IHC) HPA →
Caudate Glial cells Not detected Protein (IHC) HPA →
Skeletal muscle Myocytes Not detected Protein (IHC) HPA →
Smooth muscle Smooth muscle cells Not detected Protein (IHC) HPA →
Section 3

Advanced CYP1A1 IHC Tips

Troubleshoot CYP1A1 staining in paraffin sections by checking retrieval, compartment, controls, and scoring before interpreting signal (UniProt P04798; HPA tissue IHC).

What retrieval should I try first if CYP1A1 staining is weak?
Start with heat-mediated retrieval in citrate buffer at pH 6 for 20 minutes (datasheet PB9544). The selected paraffin-section example used that retrieval before overnight incubation with 1 µg/ml catalog antibody at 4°C (datasheet PB9544). If signal remains weak, compare retrieval durations on adjacent sections while holding antibody concentration, incubation, and detection constant; inspect tissue integrity and background alongside signal. Record heating and cooling conditions so the comparison is reproducible. Treat a stronger stain as useful only when it preserves a plausible cellular pattern and passes a no-primary control; the HPA tissue IHC profile has uncertain reliability (HPA tissue IHC).
Could fixation explain absent CYP1A1 staining in my paraffin sections?
The selected CYP1A1 image documents a paraffin-embedded section but does not state its fixative, so target-specific fixation sensitivity is unknown (datasheet PB9544). Record the actual fixative and fixation duration for each specimen, then compare similarly processed sections before changing the antibody or detection chemistry. For routine troubleshooting, check whether delayed fixation, prolonged fixation, or inconsistent processing coincides with weak staining; these are general IHC variables, not demonstrated CYP1A1 effects. Use adjacent sections with the documented citrate pH 6, 20-minute retrieval to isolate processing differences (datasheet PB9544). Do not infer fixation tolerance from CYP1A1 localisation or HPA staining patterns (UniProt P04798; HPA tissue IHC).
Which staining compartment is plausible for CYP1A1 in chromogenic IHC?
Expect a predominantly cytoplasmic pattern in tissue sections (HPA tissue IHC: general cytoplasmic expression). CYP1A1 is annotated at the endoplasmic reticulum membrane, microsome membrane, mitochondrial inner membrane, and in cytoplasm (UniProt P04798). At light-microscope resolution, a fine granular or diffuse cytoplasmic DAB pattern can therefore be plausible, but chromogenic staining alone cannot establish which organelle contains the signal. Compare staining within intact cells against adjacent unstained areas and a no-primary section, and note whether apparent signal instead follows cut edges, lumens, or debris. HPA reports uncertain tissue IHC reliability, so compartment agreement supports plausibility without proving antibody specificity (HPA tissue IHC).
How should I assess isoform coverage and epitope accessibility?
CYP1A1 has 3 annotated isoforms, and the supplied record does not map the catalog antibody epitope to any of them (UniProt P04798; datasheet PB9544). Check the antibody's immunogen or epitope documentation before claiming that staining measures all isoforms or distinguishes one isoform from another. The record lists no transmembrane segment and a glycosylation site at residue 67, but neither fact establishes where this antibody binds or whether retrieval exposes its epitope (UniProt P04798). If staining differs between specimens, compare matched processing and appropriate specificity controls before attributing the difference to isoform expression. Report the result as CYP1A1 immunoreactivity unless isoform-specific recognition has been demonstrated.
How can I adapt CYP1A1 localisation checks to multiplex IF?
For a separate IF/ICC experiment, pair CYP1A1 with a validated marker of the cell population under study; respiratory epithelial cells in bronchus show medium tissue IHC staining, although HPA rates that profile uncertain (HPA tissue IHC). Select a fluorophore in a channel with low measured tissue autofluorescence, and include single-stain and no-primary controls to assess bleed-through and background. CYP1A1 is associated with intracellular membranes and cytoplasm (UniProt P04798), so permeabilisation may be needed if the antibody epitope faces an intracellular compartment. The epitope side is unspecified here; compare gentle permeabilisation conditions and verify that cell morphology and marker localisation remain interpretable. Do not transfer the paraffin-section retrieval conditions directly to IF (datasheet PB9544).
What should I change when DAB staining is widespread?
First compare the stained section with a no-primary control and inspect whether background follows section edges, damaged regions, or tissue-wide deposits. The documented paraffin-section workflow used 10% goat serum blocking, a biotinylated secondary, a streptavidin-biotin complex, and DAB (datasheet PB9544). Include a routine endogenous peroxidase block for chromogenic detection, and assess endogenous biotin background when using the documented biotin-based system; these are general IHC checks, not CYP1A1-specific findings. If the controls are clean but staining remains diffuse, titrate primary antibody around the documented 1 µg/ml condition while keeping retrieval and development time fixed (datasheet PB9544). Evaluate whether remaining staining is cellular and cytoplasmic (HPA tissue IHC).
How should I score CYP1A1 staining across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and analysis area before scoring, and exclude folds, necrosis, and section edges using the same rules for every slide. For cell-level assessment, report the percentage of positive cells or an H-score based on staining intensity and positive-cell fraction; keep the intensity thresholds fixed across the comparison. If counting stained cells per area, report density per mm² of viable tissue and normalise to the relevant cell population when its abundance varies. Record retrieval, antibody concentration, DAB development, and imaging settings because those choices change apparent intensity (datasheet PB9544 for the documented retrieval and antibody condition). Interpret modest differences cautiously because HPA rates tissue IHC consistency as uncertain (HPA tissue IHC).
How can I distinguish convincing CYP1A1 staining from artefact?
Look for reproducible staining within intact cell cytoplasm, consistent with the HPA tissue IHC profile and CYP1A1's annotated intracellular locations (HPA tissue IHC; UniProt P04798). Check whether staining occurs in the cell population being evaluated: HPA lists medium staining in bronchial respiratory epithelial cells, but its overall tissue IHC reliability is uncertain (HPA tissue IHC). Signal confined to section edges, necrotic debris, or no-primary controls should prompt an artefact review; in DAB assays, assess endogenous peroxidase as a general source of false signal. Strong nuclear-only staining is difficult to reconcile with the supplied localisation record (UniProt P04798). Confirm consequential conclusions with an independent specificity control before treating stain intensity as CYP1A1 abundance.
Boster reagents

Best CYP1A1 / Cytochrome P450 1A1 IHC Antibodies

PB9544 has real IHC images from paraffin mouse and rat kidney and human mammary cancer sections, frozen human placenta, and IF images from Caco-2 cells (catalog image captions).

Real IHC data IHC analysis of CYP1A1 using anti-CYP1A1 antibody (PB9544). CYP1A1 was detected in paraffin-embedded section of Mouse Kidney Tissue. Heat mediated antigen retrieval was performed in citrate buffer (pH6, epitope retrieval solution) for 20 mins. The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 1μg/ml rabbit anti-CYP1A1 Antibody (PB9544) overnight at 4°C. Biotinylated goat anti-rabbit IgG was used as secondary antibody and incubated for 30 minutes at 37°C. The tissue section was developed using Strepavidin-Biotin-Complex (SABC)(Catalog # SA1022) with DAB as the chromogen.
Anti-Cytochrome P450 1A1/CYP1A1 Antibody ®
Cat # PB9544

PB9544 is listed for IHC and IHC-F in human, mouse and rat samples, with paraffin-section images from mouse kidney, rat kidney and human mammary cancer, and a frozen-section image from human placenta (catalog applications, reactivity and IHC captions). PB9544 is also listed for IF/ICC, with an IF image from Caco-2 cells (catalog applications and IF caption).

Which to pick: Choose PB9544 for paraffin-section IHC: its mouse kidney image documents citrate retrieval at pH 6 for 20 minutes and 1 μg/ml primary antibody (PB9544 IHC caption); the fixative is unreported (PB9544 IHC caption). Choose PB9544 for IF/ICC when Caco-2 image evidence is relevant; the caption documents 2 μg/ml primary antibody (PB9544 IF caption). PB9544 is listed as reactive with human, mouse and rat and for IHC, IHC-F and IF/ICC; clonality is unreported (catalog reactivity, applications and clone field).

Each figure is that product's own IHC / IF validation image from its datasheet.

References

  1. UniProt Consortium. UniProt entry P04798 (CP1A1_HUMAN, Cytochrome P450 1A1).
  2. Human Protein Atlas. CYP1A1 tissue IHC expression (reliability: Uncertain).
  3. Human Protein Atlas. CYP1A1 subcellular location (ICC-IF): Membrane.
  4. Human Protein Atlas. CYP1A1 antibody validation summary (1 antibodies).
  5. Systemic effects of arctic pollutants in beluga whales indicated by CYP1A1 expression. Environmental health perspectives 2005 — PMC1310924.
  6. Pathological Changes and CYP1A1 Expression as Biomarkers of Pollution in Sarpa Salpa and Diplodus Sargus. Animals : an open access journal from MDPI 2024 — PMC11544920.
  7. Sex-specific differences in hyperoxic lung injury in mice: implications for acute and chronic lung disease in humans. Toxicology and applied pharmacology 2013 — PMC4201582.
  8. Aryl Hydrocarbon Receptor and Autophagy-Related Protein Microtubule-Associated Protein Light Chain 3 Expression in Psoriasis. Annals of dermatology 2021 — PMC8082009.
  9. PubMed PMID:2989797 — UniProt-cited evidence.
  10. PubMed PMID:3838385 — UniProt-cited evidence.
  11. PubMed PMID:3019683 — UniProt-cited evidence.