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F2R / Proteinase-activated receptor 1 · IHC design guide
Design Immunohistochemistry for F2R
Plan chromogenic IHC for F2R with membrane localization expected (UniProt) and endothelial staining observed in tissue sections (HPA tissue IHC). Start with 0.5–1 μg/mL catalog antibody on paraffin sections (datasheet A03352-1), and assess vessel-associated staining with matched controls.
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
F2R 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 | Cell membrane expected (UniProt) | |
| Staining pattern | Blood vessel endothelial staining in several tissues (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A03352-1) | |
| Positive control | Bone marrow+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 across sections (standard IHC practice; not target-specific) | |
| Caveat | Vessel staining can complicate cell-specific scoring (HPA tissue IHC) | |
| Regulation | Staining-intensity regulation not established (UniProt) | |
| Isoform / epitope | No isoforms annotated; extracellular and cytoplasmic regions differ (UniProt) |
Section 1
Recommended F2R IHC & IF Protocols
The catalog antibody’s EDTA protocol (datasheet A03352-1) is followed by two published F2R IHC protocols (PMC11681937; PMC10827804).
| Sample | Paraffin-embedded human breast cancer tissue; fixative not specified (datasheet A03352-1) |
| Fixation | Image fixative and duration unreported (datasheet A03352-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet A03352-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A03352-1) |
| Primary antibody | Rabbit anti-F2R, 0.5-1μg/ml (datasheet A03352-1) |
| Primary incubation | Overnight at 4 °C (datasheet A03352-1) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A03352-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | F2R-positive staining in hematopoietic cells of bone marrow (HPA tissue IHC: Medium). HPA tissue profile: Expression in several tissues and in blood vessles. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA at pH 8.0 (datasheet A03352-1); citrate is a published alternative for intestinal sections (PMC11681937 methods).
Section 2
What Is the Expected F2R Staining Pattern?
F2R is a 7-transmembrane cell-surface receptor (UniProt P25116 topology; UniProt P25116 subcellular location). In paraffin-section IHC, expect staining along vascular endothelial cell boundaries (HPA tissue IHC: Approved endothelial staining; UniProt P25116 tissue specificity). HPA also reports medium staining in selected hematopoietic, stromal, glomerular, epithelial, decidual and red-pulp cells (HPA tissue IHC). Interpret those sites by cell type and compartment, since staining is not uniform across tissues (HPA tissue IHC).
| Vessel-lining cells show a boundary-associated chromogenic signal. | This fits the strongest tissue-level expectation: HPA reports approved endothelial staining and expression in blood vessels (HPA tissue IHC: Approved); a cell-boundary pattern fits F2R's membrane location (UniProt P25116 subcellular location). Compare stained vessels with neighboring cells on the same section before scoring intensity. |
| Selected nonvascular cells stain at a moderate level. | Medium staining is reported for bone-marrow hematopoietic cells, endometrial stromal cells, glomerular cells, lymph-node germinal-center cells, nasopharyngeal respiratory epithelium, placental decidual cells, skin keratinocytes and splenic red-pulp cells (HPA tissue IHC: Medium). Identify the stained cell population before calling the result concordant. |
| Signal is predominantly nuclear, with no convincing cell-boundary staining. | An isolated nuclear pattern does not match the reported membrane location (UniProt P25116 subcellular location; HPA subcellular summary: Membrane). Treat it as unresolved until controls and morphology support specificity; general IHC practice: review counterstain, precipitate and nonspecific detection before interpreting a new compartment. |
| Adipocytes or other cells listed as undetected stain strongly. | HPA lists adipocytes in adipose tissue and breast as not detected (HPA tissue IHC: Not detected). Strong staining there is discordant with those observations and warrants checks for antibody cross-reactivity or endogenous detection activity (general IHC practice). An HPA 'not detected' entry does not prove every specimen of that tissue is negative. |
| Color is diffuse across cells and surrounding tissue, without a discernible boundary pattern. | Diffuse staining gives little support for the reported membrane location (UniProt P25116 subcellular location). General IHC practice: compare with a no-primary control and inspect wash, blocking and chromogen conditions; background alone cannot identify whether the cause is nonspecific antibody binding or the detection system. |
💡Expected F2R appearanceCall a section positive when identifiable vascular endothelial cells show convincing cell-boundary staining, with medium signal possible in HPA-listed cell populations (HPA tissue IHC: Approved endothelial staining; HPA tissue IHC: Medium; UniProt P25116 subcellular location); isolated nuclear color or diffuse, cell-independent color is suspect (general IHC interpretation).
| Cell compartment and antibody epitope | F2R has extracellular and cytoplasmic regions separated by 7 transmembrane segments (UniProt P25116 topology). The supplied antibody records do not identify an epitope (HPA antibodies); therefore, topology alone cannot specify which region this assay detects or justify a particular permeabilisation choice. |
| Protein processing and modifications | UniProt lists a signal peptide, propeptide and mature chain beginning at residue 42, plus glycosylation sites and a phosphoserine (UniProt P25116 processing; UniProt P25116 glycosylation; UniProt P25116 modified residues). These annotations do not establish an IHC signal change or a target-specific fixation effect. |
| Evidence behind the tissue pattern | HPA calls endothelial tissue staining Approved and lists 2 antibodies with IHC status Approved (HPA tissue IHC: reliability; HPA antibodies: CAB008973, CAB012962). Their supplied records do not state Enhanced validation (HPA antibodies); read the tissue pattern as a reference for comparison, not proof that any new antibody is specific. |
| Retrieval and chromogenic detection | Target-specific fixation effects are not established by the supplied assay evidence. Verify with a matched IHC source before attributing a result to fixation. |
| IF/ICC applicability — what can this section predict? | Membrane localization is a reasonable compartment expectation (HPA subcellular summary: Membrane; UniProt P25116 subcellular location). HPA supplies no ICC-IF image cell lines, and the listed antibodies have no ICC status in this payload (HPA subcellular; HPA antibodies); this evidence cannot validate an IF/ICC staining result. |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in vessels of a section expected to contain F2R. | The result conflicts with HPA's approved endothelial observation, but specimen biology and assay failure cannot be distinguished from the slide alone (HPA tissue IHC: Approved). | General IHC practice: confirm vessel identification and review a known-positive section, no-primary control, reagent performance and the IHC-validated antibody's documented retrieval and dilution. |
| Only nuclear staining is visible. | A nuclear-only pattern is unsupported by the membrane localization (UniProt P25116 subcellular location; HPA subcellular summary: Membrane). | General IHC practice: inspect counterstain and precipitate, compare the no-primary control, and repeat with appropriate detection controls before assigning F2R positivity. |
| Staining appears in adipocytes but not expected vessel-lining cells. | This differs from HPA's not-detected adipocyte entries and approved endothelial staining (HPA tissue IHC). Cross-reactivity or endogenous detection activity is possible (general IHC practice). | General IHC practice: verify cell identity, run no-primary and detection controls, and compare an HPA-listed positive cell population on a separately stained section. |
| The entire section has weak, uniform color. | A uniform field cannot resolve the membrane-associated pattern expected from F2R localization (UniProt P25116 subcellular location); excess background is a practical possibility (general IHC practice). | General IHC practice: inspect blank areas and no-primary control, then review blocking, washes, detection reagents and chromogen development. |
| A reported medium-positive cell population is unstained. | HPA's medium category describes its observed staining, not a guaranteed result in every specimen or preparation (HPA tissue IHC: Medium). | General IHC practice: first confirm the cell population histologically; compare vessel staining and a separately stained positive section before changing retrieval or antibody conditions. |
| An IF/ICC result is used to judge the paraffin-section assay. | The payload supplies membrane localization but no ICC-IF image cell lines or ICC validation status for the listed antibodies (HPA subcellular; HPA antibodies). | Judge the IHC result against tissue morphology, endothelial staining and appropriate IHC controls (HPA tissue IHC: Approved; general IHC practice); evaluate IF/ICC with its own controls. |
Experiment evidence
IHC & IF images showing F2R staining
A03352-1 · IHCIHC analysis of F2R using anti-F2R antibody (A03352-1). F2R was detected in paraffin-embedded section of human breast cancer tissue. Heat me
A03352-1 · IHCIHC analysis of F2R using anti-F2R antibody (A03352-1). F2R was detected in paraffin-embedded section of human rectal cancer tissue. Heat me
RP1092 · IHCAnti-Thrombin Receptor antibody, RP1092, IHC(P) IHC(P): Human Placenta Tissue
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000181104-F2R/tissue/cerebral+cortex#imid_3888840
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000181104-F2R/tissue/colon#imid_3907062
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000181104-F2R/tissue/liver#imid_3907063
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000181104-F2R/tissue/kidney#imid_3907072
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for F2R IHC & IF
🧪Run kidney first and score staining in glomerular cells (HPA: Medium in cells in glomeruli). Run adipose tissue as the negative tissue, focusing on adipocytes (HPA: Not detected in adipocytes); on the kidney slide, use adjacent cells without specific staining as a background comparator, without treating them as a validated F2R-negative cell type.
Positive control tissue: Bone marrow (Hematopoietic 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 F2R; derive a cell-line control from the positive tissue's cell type (Hematopoietic cells) and confirm it by RNA or western blot first.
Technical controls: Include no-primary (secondary-only) and host-species-matched isotype controls, plus F2R-knockout tissue or a matched immunizing-peptide block if available (standard IHC practice). For kidney sections, quench endogenous peroxidase and block endogenous biotin when using the caption’s biotin-based DAB detection (caption: SABC/DAB; standard IHC practice).
⚠️Feasibility: A target-specific fixation window and fixation effect are unreported, and the selected A03352-1 paraffin-section caption does not state the fixative (caption: fixative not stated). The caption demonstrates heat retrieval in EDTA at pH 8.0, but does not establish whether retrieval is required (caption: EDTA pH 8.0). No matched frozen-section or IF evidence establishes that either is easier; endogenous biotin in kidney can complicate biotin-based detection (caption: SABC/DAB; standard IHC practice).
HPA tissue IHC evidence for F2R
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Antibody staining in endothelial cells, view images.). 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 |
|---|---|---|---|---|
| Bone marrow | Hematopoietic cells | Medium | Protein (IHC) | HPA → |
| Endometrium | Cells in endometrial stroma | Medium | Protein (IHC) | HPA → |
| Kidney | Cells in glomeruli | Medium | Protein (IHC) | HPA → |
| Lymph node | Germinal center cells | Medium | Protein (IHC) | HPA → |
| Nasopharynx | Respiratory epithelial cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Appendix | Glandular 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 F2R IHC Tips
Troubleshoot F2R staining in paraffin sections by checking retrieval, cell identity, membrane localisation and detection controls (UniProt P25116; HPA tissue IHC).
How should I retrieve F2R in paraffin sections when staining is weak?
Start with heat-mediated retrieval in EDTA pH 8.0 (datasheet A03352-1). The documented paraffin-section workflow then used 1 μg/mL catalog antibody overnight at 4°C, so hold those conditions constant while assessing retrieval (datasheet A03352-1). Compare an untreated section with sections receiving progressively longer heating under the same EDTA condition, and judge improvement in vessel-associated cells rather than overall brown intensity (standard IHC practice; HPA: staining in endothelial cells). If staining remains weak, test a second retrieval condition as a fallback on matched sections, recording its buffer, pH and heating time; reject conditions that damage morphology or increase diffuse background (standard IHC practice).
Could fixation explain weak F2R staining in my paraffin sections?
F2R-specific sensitivity to fixative type or fixation duration is unknown from the supplied evidence; the catalog paraffin-section caption does not state its fixative (datasheet A03352-1). Record the fixative and duration for each specimen, then compare sections processed together with the same EDTA pH 8.0 retrieval and 1 μg/mL antibody condition (datasheet A03352-1; standard IHC practice). Examine morphology alongside staining, because poorly preserved tissue makes membrane-associated signal difficult to assign to cells (standard IHC practice; UniProt P25116: cell membrane). Treat any association between fixation and signal as an observation requiring matched specimens, rather than an established F2R-specific fixation effect (standard IHC practice).
What F2R staining pattern should I expect in tissue sections?
Prioritise staining associated with cell boundaries: F2R is annotated at the cell membrane and contains 7 transmembrane segments (UniProt P25116 topology and subcellular location). Vascular endothelial cells are a useful compartment to inspect because they are listed in the tissue specificity record and highlighted in the tissue staining assessment (UniProt P25116 tissue specificity; HPA: approved endothelial-cell staining). Use the counterstain and adjacent tissue architecture to distinguish a vessel lining from surrounding cells before assigning positivity (standard IHC practice). Predominantly nuclear or uniformly diffuse stromal DAB should prompt review of controls, retrieval and detection background before it is scored as F2R (UniProt P25116: cell membrane; standard IHC practice).
How do F2R processing and epitope position affect my IHC result?
F2R has 0 annotated isoforms, so an unexpected staining pattern should not be assigned to a documented splice variant (UniProt P25116 isoforms). Its signal peptide spans residues 1–21, propeptide 22–41, and annotated receptor chain 42–425 (UniProt P25116 processing). Extracellular segments include residues 42–102 and 240–268, while the carboxyl terminus 375–425 is cytoplasmic; the record also lists glycosylation sites and phosphoserine 418 (UniProt P25116 topology and modifications). Check the antibody’s stated immunogen or mapped epitope before interpreting loss of staining, because the supplied catalog caption does not identify the epitope (datasheet A03352-1; standard IHC practice).
How can I assess F2R by multiplex IF alongside a cell-type marker?
For the separate IF/ICC application, pair F2R with a validated marker that identifies the expected endothelial cells, and inspect whether the signals align at cell boundaries (HPA: endothelial-cell staining; UniProt P25116: cell membrane; standard IF practice). Choose spectrally separated fluorophores after checking tissue autofluorescence with an unstained section, assigning the clearer channel to the weaker signal (standard IF practice). If the antibody epitope is extracellular, compare staining with minimal permeabilisation; if it is cytoplasmic, optimise permeabilisation against membrane preservation (UniProt P25116 topology; standard IF practice). Confirm the antibody’s epitope first, since the supplied paraffin-section caption does not specify it or establish an IF protocol (datasheet A03352-1).
How can I distinguish F2R signal from chromogenic background?
Compare a no-primary control with the stained section to identify signal arising from the detection system, and include a tissue region expected to have limited staining when available (standard IHC practice). The documented method used a biotinylated secondary antibody, streptavidin–biotin detection and DAB, so inspect diffuse deposits and run appropriate detection controls before attributing brown staining to F2R (datasheet A03352-1; standard IHC practice). Block endogenous peroxidase as a general chromogenic IHC step, and assess whether biotin-dependent background affects the chosen system (standard IHC practice). Retain the documented 10% goat-serum block and 1 μg/mL primary antibody as reference conditions while changing one background-control step at a time (datasheet A03352-1).
What is a defensible way to quantify F2R IHC across samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the scored compartment before analysis, such as morphologically identified vessel-lining cells, because F2R is membrane-associated and endothelial staining has tissue-IHC support (UniProt P25116: cell membrane; HPA: approved endothelial-cell staining; standard IHC practice). Report the percentage of positive cells and an intensity-based H-score if cell boundaries can be assessed consistently, using the same thresholds across slides (standard IHC practice). For vessel-focused measurements, report positive-cell density per mm² of analysed vessel-associated area and the sampled area, rather than raw DAB counts (standard IHC practice). Normalise to the relevant cell population or analysed area, exclude folds and necrosis, and keep retrieval at EDTA pH 8.0 across comparisons (standard IHC practice; datasheet A03352-1).
When should I doubt an apparent F2R-positive IHC result?
Give greatest weight to cell-boundary staining in an anatomically identifiable cell population, particularly vessel-lining cells, consistent with F2R membrane localisation and the endothelial tissue-IHC assessment (UniProt P25116: cell membrane; HPA: approved endothelial-cell staining; standard IHC practice). Question predominantly nuclear staining, broad necrotic deposits and staining confined to section edges, and check whether the no-primary control reproduces the pattern (UniProt P25116: cell membrane; standard IHC practice). In the documented DAB workflow, endogenous peroxidase or detection-system staining can mimic positivity unless appropriate controls are assessed (datasheet A03352-1; standard IHC practice). A paraffin-section breast-cancer image shows that the catalog antibody was used there; it does not establish positivity in every cell of that specimen (datasheet A03352-1).
Boster reagents
Best F2R / Proteinase-activated receptor 1 IHC Antibodies
Two anti-F2R antibodies have IHC images from human paraffin sections; catalog reactivity covers human, mouse and rat, but neither lists IF/ICC (catalog applications, reactivity and IHC captions).
Real IHC data
Anti-PAR1/Thrombin Receptor/F2R Antibody ®
Cat # A03352-1
Real IHC data
Anti-Thrombin Receptor/F2R Antibody ®
Cat # RP1092
A03352-1 is listed for IHC and has images from paraffin sections of human breast and rectal cancer (A03352-1 applications and IHC captions). RP1092 is listed for IHC and has an image from human placenta (RP1092 applications and IHC caption).
Which to pick: For human paraffin-section IHC, choose A03352-1 when its breast or rectal cancer examples are relevant; RP1092 has a human placenta example (respective IHC captions). For cross-species work, A03352-1 lists human, mouse and rat reactivity, while RP1092 lists human only; the supplied IHC images show human tissue, so verify staining in other species (catalog reactivity and IHC captions). Neither SKU lists IF/ICC, and neither IHC caption reports the fixative (catalog applications and IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P25116 (PAR1_HUMAN, Proteinase-activated receptor 1).
- Human Protein Atlas. F2R tissue IHC expression (reliability: Approved).
- Human Protein Atlas. F2R subcellular location (ICC-IF): Membrane.
- Human Protein Atlas. F2R antibody validation summary (2 antibodies).
- Ameloblast transcriptome changes from secretory to maturation stages. Connective tissue research 2014 — PMC4252044.
- Uncovering novel therapeutic clues for hypercoagulable active ulcerative colitis: novel findings from old data. Gastroenterology report 2024 — PMC11681937.
- Bioinformatics analysis identifies coagulation factor II receptor as a potential biomarker in stomach adenocarcinoma. Scientific reports 2024 — PMC10827804.
- Heterogeneity induced GZMA-F2R communication inefficient impairs antitumor immunotherapy of PD-1 mAb through JAK2/STAT1 signal suppression in hepatocellular carcinoma. Cell death & disease 2022 — PMC8901912.
- PubMed PMID:1672265 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
- PubMed PMID:7744748 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for F2R (Proteinase-activated receptor 1). Expected localisation Cell membrane expected (UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A03352-1). Validated IHC antibody: A03352-1 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Bone marrow (Hematopoietic cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human breast cancer tissue; fixative not specified (datasheet A03352-1); 2. Fixation: Image fixative and duration unreported (datasheet A03352-1); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat retrieval: EDTA pH 8.0 (datasheet A03352-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A03352-1); 8. Primary antibody: Rabbit anti-F2R, 0.5-1μg/ml (datasheet A03352-1); 9. Primary incubation: Overnight at 4 °C (datasheet A03352-1). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Vessel staining can complicate cell-specific scoring (HPA tissue IHC); Isoform / epitope: No isoforms annotated; extracellular and cytoplasmic regions differ (UniProt); Regulation: Staining-intensity regulation not established (UniProt). Evidence: UniProt P25116, HPA tissue IHC · Approved, HPA ICC-IF · Membrane, Datasheet A03352-1, PMC11681937, PMC10827804. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/F2R/immunohistochemistry-ihc-guide.