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PGRMC1 / Membrane-associated progesterone receptor component 1 · IHC design guide
Design Immunohistochemistry for PGRMC1
Plan PGRMC1 staining in paraffin sections using the observed cytoplasmic tissue pattern (HPA tissue IHC). Compare cells within each tissue and account for the reported secreted variant when interpreting signal (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
PGRMC1 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) | |
| Staining pattern | Cytoplasmic staining across diverse tissue cell types (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet PB9775) | |
| Positive control | Cerebellum+4 more · see all | |
| Negative control | Heart muscle+1 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across paraffin sections. (standard IHC practice; not target-specific) | |
| Caveat | A secreted variant may complicate tissue staining (HPA tissue IHC) | |
| Regulation | Liver-enhanced RNA; staining may vary (HPA tissue RNA + IHC) | |
| Isoform / epitope | 2 isoforms; epitope map unspecified (UniProt) |
Section 1
Recommended PGRMC1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is paired with published staining details for tissue sections and canine tissue sections (PMC3203473; PMC4908248).
| Sample | Paraffin-embedded human colon cancer tissue; fixative not specified (datasheet PB9775) |
| Fixation | Image fixative and duration unreported (datasheet PB9775); 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 PB9775); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet PB9775) |
| Primary antibody | Rabbit anti-PGRMC1, 2-5μg/ml (datasheet PB9775) |
| Primary incubation | Overnight at 4 °C (datasheet PB9775) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet PB9775) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | PGRMC1-positive staining in gLUC cells - cytoplasm/membrane of cerebellum (HPA tissue IHC: High). HPA tissue profile: Ubiquitous cytoplasmic expression. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval for the catalog antibody (datasheet: PB9775); neither included article excerpt specifies retrieval.
Section 2
What Is the Expected PGRMC1 Staining Pattern?
In paraffin sections, expect predominantly cytoplasmic PGRMC1 staining in endometrial stromal cells, liver cholangiocytes, kidney Bowman’s capsule cells and testicular Leydig cells (HPA: High in each). A membrane-associated pattern is biologically plausible because PGRMC1 has one transmembrane segment and a cytoplasmic region (UniProt O00264 topology). HPA calls the tissue profile ubiquitous cytoplasmic expression, with Enhanced reliability but only medium agreement between staining and RNA data (HPA: tissue IHC).
| Distinct cytoplasmic staining in endometrial stromal cells or cholangiocytes, with tissue structure still clear. | This fits high staining reported in those cell populations (HPA: High in endometrial stroma; High in cholangiocytes). Compare cells within the section: HPA reports a broadly cytoplasmic profile, so a positive call should rest on recognizable cellular staining rather than color anywhere in the tissue (HPA: ubiquitous cytoplasmic expression; general IHC interpretation). |
| Signal appears mainly nuclear, without convincing cytoplasmic staining, in an otherwise interpretable section. | Treat nuclear-only chromogenic staining as discordant with the expected tissue pattern and investigate assay background before scoring it as PGRMC1 (HPA: ubiquitous cytoplasmic expression). HPA reports nucleoli as an additional location in ICC-IF, but that finding alone does not establish nuclear-only staining as the expected paraffin IHC result (HPA: subcellular ICC-IF). |
| Strong stain dominates cardiomyocytes or vaginal squamous epithelium while expected positive cells are faint. | These populations are reported as not detected, so this distribution raises concern for cross-reactivity or endogenous detection activity (HPA: Not detected in cardiomyocytes and vaginal squamous epithelial cells; general IHC practice). Recheck the same run against a known-positive tissue; HPA staining levels describe observed patterns, not an absolute exclusion of expression in every specimen (HPA: tissue IHC). |
| Uniform color covers stroma, lumens, edges or many cell types and obscures cellular boundaries. | This is difficult to score as a cytoplasmic PGRMC1 pattern (HPA: ubiquitous cytoplasmic expression; general IHC interpretation). Excess detection background, incomplete blocking or retained reagent can produce nonspecific color in chromogenic IHC (general IHC practice). Assess reagent controls and tissue morphology before interpreting weak cell-associated signal (general IHC practice). |
| No staining appears in endometrial stromal cells, cholangiocytes or Leydig cells. | An absent signal in a suitable positive-control section conflicts with HPA’s high staining in those cells (HPA: High in endometrial stroma, cholangiocytes and Leydig cells). First evaluate section integrity, reagent performance and detection controls (general IHC practice). A failed positive control makes a negative result in the test specimen inconclusive (general IHC interpretation). |
💡Expected PGRMC1 appearanceCall the slide positive when recognizable cells show predominantly cytoplasmic staining, especially strong staining in HPA high populations such as endometrial stromal cells or cholangiocytes; widespread acellular color or isolated nuclear-only stain is suspect (HPA: tissue IHC; general IHC interpretation).
| Which cells provide useful pattern anchors? | HPA reports high staining in endometrial stroma, cholangiocytes, Bowman’s capsule, Leydig cells, seminal-vesicle glandular cells and skin fibrohistiocytic cells; adipocytes are medium, while cardiomyocytes and vaginal squamous epithelial cells are not detected (HPA: tissue IHC). Choose a control with identifiable positive cells and assess those cells specifically (general IHC practice). |
| How should membrane or unusual compartment staining be weighed? | PGRMC1 has a transmembrane segment at residues 25–43 and a cytoplasmic region at 44–195 (UniProt O00264 topology). UniProt also places it at microsome, smooth ER and mitochondrial outer membranes, and notes cell-membrane localization under serum-starved conditions (UniProt O00264 subcellular location). These locations do not make nuclear-only paraffin staining an expected result (HPA: tissue IHC; general IHC interpretation). |
| Do variant or secreted-protein annotations affect scoring? | UniProt lists two isoforms and a secreted location (UniProt O00264 isoforms and subcellular location). HPA notes that at least one protein variant is secreted and that protein and RNA locations may differ (HPA: Enhanced reliability description). Interpret extracellular staining cautiously and do not require RNA and chromogenic staining to match cell for cell (HPA: tissue IHC). |
| What does antibody validation establish? | Two listed rabbit polyclonal antibodies, HPA002877 and HPA064724, have Enhanced IHC validation (HPA: antibody validation). Enhanced means the pattern is supported by independent antibodies or orthogonal data (HPA: IHC validation summary). It supports the reported pattern; it does not provide a dilution, retrieval condition or guarantee specificity in every specimen (HPA: supplied antibody data; general IHC interpretation). |
| IF/ICC Q&A: what localization can be used for a cross-check? | HPA reports endoplasmic reticulum as the main approved ICC-IF location, with nucleoli, sperm mid piece and principal piece as additional approved locations (HPA: subcellular ICC-IF). Use those observations to interpret an IF/ICC image; they do not specify a paraffin IHC retrieval or detection protocol (HPA: subcellular ICC-IF; general IHC practice). |
| Situation | Likely cause | Next action |
|---|---|---|
| Known-positive cells are unstained. | The positive control has failed, leaving a test-tissue negative call unresolved (HPA: High in endometrial stroma and cholangiocytes; general IHC interpretation). | Check section integrity, antibody application, detection reagents and chromogen with the run controls; then repeat the affected run (general IHC practice). Do not assign a PGRMC1-negative result until the expected positive cells stain (HPA: tissue IHC; general IHC interpretation). |
| Staining is weak in a reported high population. | Assay performance or specimen condition may limit visible signal; HPA’s high category does not prescribe intensity for every section (HPA: tissue IHC; general IHC interpretation). | Compare a concurrently processed positive control and tissue morphology, then review the catalog antibody’s IHC-P instructions for dilution and retrieval if available (general IHC practice). No PGRMC1-specific fixation sensitivity is established by these sources (HPA: supplied tissue IHC; UniProt O00264). |
| Brown color appears across lumens or blank tissue spaces. | Acellular color is inconsistent with HPA’s cytoplasmic cellular profile and may reflect nonspecific background (HPA: ubiquitous cytoplasmic expression; general IHC practice). | Inspect reagent and negative controls; review blocking, washes and detection steps before lowering the threshold for a positive call (general IHC practice). Score recognizable cells rather than deposited color alone (general IHC interpretation). |
| Cardiomyocytes or vaginal squamous cells stain strongly. | This conflicts with HPA’s not-detected observations in those cell types; cross-reactivity or endogenous detection activity is possible (HPA: heart muscle and vagina IHC; general IHC practice). | Check a reagent-control section and the expected positive-cell pattern in the same run; investigate endogenous activity appropriate to the detection chemistry (general IHC practice). Treat the unexpected stain as unresolved until those checks pass (general IHC interpretation). |
| Only nuclei stain in paraffin sections. | Nuclear-only staining conflicts with the reported ubiquitous cytoplasmic tissue pattern, although HPA separately reports nucleoli in ICC-IF (HPA: tissue IHC; HPA: subcellular ICC-IF). | Review morphology and reagent controls, and compare with cytoplasmic staining in a known-positive population before assigning specificity (general IHC practice; HPA: High in endometrial stroma). |
| Protein staining and RNA abundance appear to disagree. | HPA reports medium consistency between antibody staining and RNA data and notes a secreted variant; protein and RNA locations can differ (HPA: Enhanced reliability description). | Base the IHC call on cell-resolved staining, controls and the reported protein pattern; describe any RNA discrepancy without treating it alone as assay failure (HPA: tissue IHC; general IHC interpretation). |
Experiment evidence
IHC & IF images showing PGRMC1 staining
PB9775 · IHCIHC analysis of PGRMC1 using anti-PGRMC1 antibody (PB9775). PGRMC1 was detected in a paraffin-embedded section of human colon cancer tissue.
PB9775 · IHCIHC analysis of PGRMC1 using anti-PGRMC1 antibody (PB9775). PGRMC1 was detected in a paraffin-embedded section of human colon cancer tissue.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000101856-PGRMC1/tissue/cerebral+cortex#imid_957792
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000101856-PGRMC1/tissue/colon#imid_957726
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000101856-PGRMC1/tissue/liver#imid_957735
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000101856-PGRMC1/tissue/kidney#imid_957728
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA002877; green = PGRMC1, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA002877; green = PGRMC1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for PGRMC1 IHC & IF
🧪Run endometrium first and score stromal cells for PGRMC1 staining (HPA: High in cells in endometrial stroma). Use heart muscle cardiomyocytes as the negative tissue (HPA: Not detected in cardiomyocytes); any independently verified negative cells on the endometrial slide should show counterstain without specific DAB signal, but endometrial glands cannot be assumed negative (UniProt O00264: expression in glands and stroma).
Positive control tissue: Cerebellum (GLUC cells - cytoplasm/membrane, HPA High)
Negative control tissue: Heart muscle (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show PGRMC1 in A-431, U-251MG, U2OS, HEK293, Sperm, with annotated localisation: Endoplasmic reticulum (approved) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a rabbit immunoglobulin isotype control matched to the primary antibody’s class and clonality when known (caption: rabbit primary and anti-rabbit secondary; standard IHC practice). Confirm biological specificity with PGRMC1 knockout tissue or a validated peptide block, and quench endogenous peroxidase before HRP/DAB detection in the endometrial section (standard IHC practice; caption: HRP/DAB detection).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected PB9775 paraffin-section caption does not state the fixative (caption: fixative unreported). The caption uses heat retrieval in EDTA at pH 8.0, but does not establish that retrieval is required (caption: EDTA retrieval at pH 8.0). Whether frozen sections or IF are easier is unreported; assess background from endogenous peroxidase in this HRP/DAB assay (caption: HRP/DAB detection; standard IHC practice).
HPA tissue IHC evidence for PGRMC1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. At least one protein variant secreted, tissue location of RNA and protein might differ and correlation is complex.). 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 |
|---|---|---|---|---|
| Cerebellum | GLUC cells - cytoplasm/membrane | High | Protein (IHC) | HPA → |
| Endometrium | Cells in endometrial stroma | High | Protein (IHC) | HPA → |
| Kidney | Bowman's capsule | High | Protein (IHC) | HPA → |
| Liver | Cholangiocytes | High | Protein (IHC) | HPA → |
| Seminal vesicle | Glandular cells | High | Protein (IHC) | HPA → |
Section 3
Advanced PGRMC1 IHC Tips
Troubleshoot PGRMC1 staining in paraffin sections by checking retrieval, controls, cellular localisation and scoring before interpreting chromogenic signal.
What should I change when PGRMC1 staining is weak after antigen retrieval?
Use heat-mediated antigen retrieval in EDTA at pH 8.0 for paraffin-section PGRMC1 IHC (datasheet PB9775). Keep retrieval conditions consistent while checking whether a positive control and the section under investigation were processed together; the selected image used 2 μg/ml primary antibody overnight at 4°C (caption PB9775). If staining remains weak, compare a longer retrieval time or an alternative buffer on adjacent sections, watching for tissue damage. Assess cytoplasmic staining in an expected positive population, such as endometrial stromal cells, rather than judging retrieval from total section darkness (HPA: high in endometrial stroma; ubiquitous cytoplasmic expression).
Could fixation explain weak PGRMC1 staining in my paraffin sections?
The selected paraffin-section image does not report its fixative, so target-specific PGRMC1 fixation sensitivity is unknown (caption PB9775). Record the fixative, fixation duration and processing history for each specimen, then compare sections prepared under matched conditions before changing the antibody concentration. If morphology is preserved but signal is weak, first repeat the documented EDTA pH 8.0 retrieval and 2 μg/ml primary incubation overnight at 4°C on a control section (caption PB9775). A processing comparison can identify a practical cause of signal loss, but it cannot establish a PGRMC1-specific fixation effect without direct evidence.
Where should convincing PGRMC1 chromogenic signal appear?
Expect mainly cytoplasmic staining in tissue IHC, while recognising that PGRMC1 is associated with microsomal and smooth endoplasmic reticulum membranes and the mitochondrial outer membrane (HPA: ubiquitous cytoplasmic expression; UniProt O00264: subcellular location). Its membrane topology places residues 1–24 on the lumenal side and 44–195 on the cytoplasmic side of a 25–43 transmembrane segment (UniProt O00264: topology). Score the predominant pattern within defined cells before assigning significance to isolated membrane or nuclear colour. Cell-membrane localisation has been reported under serum-starved conditions, so diffuse membrane staining in a paraffin section needs corroboration rather than automatic acceptance (UniProt O00264: subcellular location).
How do isoforms and epitope position affect PGRMC1 IHC interpretation?
PGRMC1 has 2 listed isoforms, so establish which sequence region the antibody recognises before treating absent staining as absent protein (UniProt O00264: isoforms). The protein has a lumenal 1–24 region, a 25–43 transmembrane segment and a cytoplasmic 44–195 region; the cytochrome b5 heme-binding domain spans 72–171 (UniProt O00264: topology and domains). Phosphorylation is reported at residues 54, 57, 74 and 181, but the supplied evidence does not establish whether these modifications alter this antibody’s IHC signal (UniProt O00264: modified residues). Compare staining only after confirming epitope coverage and using the same retrieval conditions across specimens.
How should I investigate PGRMC1 localisation by IF alongside this IHC guide?
Treat IF/ICC as a separate validation task: the supplied PB9775 image documents chromogenic IHC in a paraffin section, with no IF result or fixative stated (caption PB9775). Multiplex PGRMC1 with a marker for the cell population being examined, such as a cholangiocyte marker in liver, where cholangiocytes show high tissue-IHC staining (HPA: high in cholangiocytes). Choose a far-red fluorophore and include an unstained section to assess tissue autofluorescence before interpreting overlap. If the antibody epitope is cytoplasmic, optimise permeabilisation for access to residues 44–195; a lumenal epitope at residues 1–24 may need different access conditions (UniProt O00264: topology).
How can I reduce diffuse brown background without losing PGRMC1 signal?
Start by comparing a no-primary control with the stained section and checking whether brown deposit follows tissue structures or pools at folds and edges. For HRP and DAB detection, include a peroxidase block and titrate primary antibody or detection reagents if background persists; these are general chromogenic IHC steps, while the selected image used 2 μg/ml primary, 10% goat serum and DAB (caption PB9775). Keep EDTA retrieval at pH 8.0 as the initial reference condition (datasheet PB9775). Because tissue expression is described as ubiquitous and cytoplasmic, a darker section alone is weak evidence of greater PGRMC1 expression (HPA: tissue IHC profile).
What is a defensible way to quantify PGRMC1 staining across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, then record the percentage of positive cells and staining intensity for an H-score or another prespecified score. If the question concerns distribution, report positive cells per mm² of viable tissue and normalise counts to the annotated tissue area; compare like cell populations across sections. PGRMC1 tissue-IHC expression is described as ubiquitous and cytoplasmic, with high staining in endometrial stromal cells and cholangiocytes (HPA: tissue IHC profile). Keep retrieval at EDTA pH 8.0, detection settings and scoring thresholds consistent, and exclude folds, necrosis and section edges from the measured area (datasheet PB9775; standard IHC practice).
When is an apparent PGRMC1-positive cell likely to be an artefact?
First ask whether the deposit lies within a plausible cell and compartment: tissue IHC shows ubiquitous cytoplasmic expression, including high staining in endometrial stromal cells, while cardiomyocytes are reported as not detected (HPA: tissue IHC profile). A signal confined to section edges, folds or necrotic areas should prompt a morphology and no-primary-control check before it is counted. Brown staining that persists in the no-primary control can reflect endogenous enzyme activity or detection background, especially when using the documented HRP and DAB workflow (caption PB9775; standard IHC practice). Corroborate unexpected nuclear-only staining independently; the approved main IF location is endoplasmic reticulum, with nucleolar localisation also reported (HPA: subcellular localisation).
Boster reagents
Best PGRMC1 / Membrane-associated progesterone receptor component 1 IHC Antibodies
PB9775 has real IHC images from human paraffin sections and is listed for human IF (PB9775 IHC captions; catalog applications). Mouse and rat reactivity is listed (catalog reactivity).
Real IHC data
Anti-PGRMC1 Antibody ®
Cat # PB9775
PB9775 is listed for IHC and IF, with human, mouse and rat reactivity (catalog applications/reactivity). Its IHC images show human colon and renal cancer paraffin sections; no IF image is supplied (PB9775 IHC/IF image captions).
Which to pick: For tissue IHC, choose PB9775: its own captions document human paraffin sections, while the fixative is unreported (PB9775 IHC captions). For human IF, PB9775 is listed at 5 μg/ml; ICC validation is unreported (catalog dilution/applications). For mouse or rat work, PB9775 has listed reactivity, but the supplied IHC images and application-specific dilutions concern human samples (catalog reactivity/dilution; PB9775 IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry O00264 (PGRC1_HUMAN, Membrane-associated progesterone receptor component 1).
- Human Protein Atlas. PGRMC1 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. PGRMC1 subcellular location (ICC-IF): Mainly localized to the endoplasmic reticulum. In addition localized to the nucleoli, mid piece and principal piece..
- Human Protein Atlas. PGRMC1 antibody validation summary (2 antibodies).
- Expression of progesterone receptor membrane component-1 in bovine reproductive system during estrous cycle. European journal of histochemistry : EJH 2011 — PMC3203473.
- Expression of Progesterone Receptor Membrane Component 1 (PGRMC1), Progestin and AdipoQ Receptor 7 (PAQPR7), and Plasminogen Activator Inhibitor 1 RNA-Binding Protein (PAIRBP1) in Glioma Spheroids In Vitro. BioMed research international 2016 — PMC4908248.
- Progesterone Receptor Membrane Component 1 (PGRMC1) Expression in Murine Retina. Current eye research 2016 — PMC4896862.
- Progesterone receptor membrane component 1 as a potential prognostic biomarker for hepatocellular carcinoma. World journal of gastroenterology 2018 — PMC5850134.
- PubMed PMID:9705155 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:15772651 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for PGRMC1 (Membrane-associated progesterone receptor component 1). Expected localisation Cytoplasmic tissue staining (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet PB9775). Validated IHC antibody: PB9775 at 2-5μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Cerebellum (GLUC cells - cytoplasm/membrane); negative Heart muscle. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Paraffin-embedded human colon cancer tissue; fixative not specified (datasheet PB9775); 2. Fixation: Image fixative and duration unreported (datasheet PB9775); 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 PB9775); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet PB9775); 8. Primary antibody: Rabbit anti-PGRMC1, 2-5μg/ml (datasheet PB9775); 9. Primary incubation: Overnight at 4 °C (datasheet PB9775). Watch for: Fixation: Keep fixation consistent across paraffin sections. (standard IHC practice; not target-specific); Caveat: A secreted variant may complicate tissue staining (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope map unspecified (UniProt); Regulation: Liver-enhanced RNA; staining may vary (HPA tissue RNA + IHC). Evidence: UniProt O00264, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the endoplasmic reticulum. In addition localized…, Datasheet PB9775, PMC3203473, PMC4908248. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/PGRMC1/immunohistochemistry-ihc-guide.