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PKP2 / Plakophilin-2 · IHC design guide
Design Immunohistochemistry for PKP2
Plan PKP2 staining in paraffin sections using its reported cytoplasmic and cardiac intercalated-disc pattern (HPA tissue IHC). The guide covers control selection and interpretation alongside the catalog antibody’s IHC conditions (datasheet A02146-2).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
PKP2 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; cardiac intercalated discs (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining in several tissues; strong cardiac discs (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A02146-2) | |
| Positive control | Cerebellum+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep paraffin-section fixation consistent. (standard IHC practice; not target-specific) | |
| Caveat | Staining and RNA expression show medium consistency (HPA tissue IHC) | |
| Regulation | Heart muscle–enhanced RNA expression (HPA tissue RNA) | |
| Isoform / epitope | 2 isoforms; epitope coverage is unspecified (UniProt; datasheet A02146-2) |
Section 1
Recommended PKP2 IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol (datasheet: A02146-2) with four published PKP2 IHC methods (PMC7568375; PMC3025932; PMC7837596; PMC10948840).
| Sample | Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet A02146-2) |
| Fixation | Image fixative and duration unreported (datasheet A02146-2); 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 A02146-2); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A02146-2) |
| Primary antibody | Rabbit anti-PKP2, 2-5 μg/ml (datasheet A02146-2) |
| Primary incubation | Overnight at 4 °C (datasheet A02146-2) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A02146-2) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | PKP2-positive staining in processes in granular layer of cerebellum (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in several tissues, highly expressed in fallopian tube and intercalated discs in cardiac muscle. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA retrieval at pH 8.0 (datasheet: A02146-2). If needed, evaluate the published citrate method at pH 6.0 (PMC3025932).
Section 2
What Is the Expected PKP2 Staining Pattern?
PKP2 should mark cell junctions, especially cardiomyocyte intercalated discs, with cytoplasmic staining possible across several tissues (UniProt Q99959 localization; HPA tissue IHC). Nuclear staining can also occur (UniProt Q99959 localization). HPA rates the tissue IHC profile Enhanced, while reporting medium consistency between staining and RNA expression (HPA tissue IHC). PKP2 has no transmembrane segment (UniProt Q99959 topology).
| Sharp staining at cardiomyocyte intercalated discs, with signal in cardiomyocytes (HPA tissue IHC). | This is the strongest anatomical check: UniProt places PKP2 at cardiac intercalated discs, and HPA reports High cardiomyocyte staining (UniProt Q99959 localization; HPA tissue IHC). Judge the junctional pattern together with the stained cell type; intensity alone cannot establish specificity. |
| Signal in fallopian tube ciliated cell bodies or nasopharyngeal ciliary rootlets (HPA tissue IHC). | Both are reported High by HPA, so they offer additional positive patterns when those tissues are available (HPA tissue IHC). Their appearance need not resemble cardiac discs: compare staining with the expected cells and structures in each tissue, rather than requiring one pattern everywhere. |
| Predominantly diffuse extracellular staining, or signal confined to an unexpected compartment in a known-positive cell. | Treat this as suspect because PKP2 is reported at junctions, in cytoplasm, and in nuclei, with no transmembrane segment (UniProt Q99959 localization and topology). Nuclear signal alone is not automatically artefact: nucleoplasmic localization is supported by HPA ICC-IF (HPA subcellular). |
| Strong staining in cells reported as undetected, with little signal in adjacent expected-positive cells. | Cross-reactivity or endogenous detection activity is possible, but a single unexpected field is not proof. HPA reports adipocytes and bone-marrow hematopoietic cells as Not detected; it also reports some other cell populations in those organs separately (HPA tissue IHC). Compare the exact cell type before interpreting a negative control. |
| A uniform haze across cells and surrounding tissue, or no staining in a known-positive section. | Uniform haze weakens compartment-level interpretation; absent signal in heart cardiomyocytes or fallopian tube ciliated cells warrants a technical check (HPA tissue IHC). Neither pattern alone proves PKP2 absence. Compare morphology, the detection blank, and a matched positive section before scoring the sample. |
💡Expected PKP2 appearanceCall a convincing positive when correctly identified cardiomyocytes show distinct intercalated-disc staining, ideally strong as in HPA's High category (UniProt Q99959 localization; HPA tissue IHC); diffuse extracellular color or equally strong staining of expected-negative cells is suspect, while weaker cytoplasmic or nuclear signal need not be false (UniProt Q99959 localization; HPA tissue IHC; HPA subcellular).
| Tissue and cell selection (HPA tissue IHC) | HPA reports High signal in heart cardiomyocytes and fallopian tube ciliated cells, but Not detected in adipocytes and bone-marrow hematopoietic cells (HPA tissue IHC). Use named cell populations as comparators; an organ label alone can obscure different cell types. |
| Localization and molecular topology (UniProt Q99959) | PKP2 is junctional, cytoplasmic and nuclear, and has no transmembrane segment or signal peptide (UniProt Q99959 localization, topology and processing). Evaluate intracellular and junctional signal; do not interpret extracellular deposits as a predicted PKP2 compartment. |
| Antibody validation and molecular variation (HPA antibodies; UniProt Q99959) | HPA rates IHC for HPA014314, HPA056908 and CAB037336 Enhanced (HPA antibodies). UniProt lists two isoforms and modified residues, but the supplied record gives no epitope map; it cannot predict isoform-specific staining or a retrieval response (UniProt Q99959 isoforms and modified residues). |
| IF/ICC Q&A: where should fluorescence appear? (HPA subcellular) | HPA reports enhanced cell-junction and supported nucleoplasmic localization, with images from A-431, CACO-2 and U2OS (HPA subcellular). That is an IF/ICC interpretation cue; this section supplies no IF/ICC protocol or dilution. |
| Situation | Likely cause | Next action |
|---|---|---|
| No chromogenic signal in heart cardiomyocytes or fallopian tube ciliated cells (HPA tissue IHC). | Target-specific fixation effects are not established by the supplied assay evidence. Verify with a matched IHC source before attributing a result to fixation. | Check section integrity, primary-antibody application, reagent activity and a matched positive section. Review antigen retrieval as a general IHC workflow variable; do not assume a PKP2-specific retrieval requirement. |
| Cardiac tissue stains, but intercalated discs are hard to distinguish (UniProt Q99959 localization). | Diffuse chromogen or poor structural preservation can obscure a junctional pattern. HPA's High cardiomyocyte category describes staining level; it does not guarantee every field will display clearly resolved discs (HPA tissue IHC). | Inspect well-preserved cardiomyocyte borders and counterstained morphology. Compare signal at intercalated discs with surrounding cytoplasm before calling the expected pattern (UniProt Q99959 localization). |
| Apparent positive staining in adipocytes or bone-marrow hematopoietic cells (HPA tissue IHC). | These named populations are Not detected in HPA; mistaken cell identification, nonspecific primary binding or endogenous detection activity could explain the result (HPA tissue IHC). | Confirm the cell identity and compare a no-primary detection control with a positive section. If staining persists only with primary antibody, reassess specificity using an independently validated antibody. |
| Broad brown haze or staining beyond recognizable cellular structures. | Background from detection reagents, inadequate blocking or overly concentrated primary antibody can obscure a cellular readout; this is a general IHC diagnostic, not a reported PKP2 property. | Compare the no-primary control, inspect reagent background and optimize blocking, washing and antibody dilution according to the chosen assay. Score PKP2 only where the expected cells and compartments remain discernible. |
| Nuclear signal appears alongside cell-border staining. | Nuclear localization is annotated by UniProt, and HPA ICC-IF supports nucleoplasmic signal (UniProt Q99959 localization; HPA subcellular). Its presence alone is therefore insufficient to label the stain nonspecific. | Check whether junctional staining also fits the tissue and cell type. Use morphology and the detection blank to distinguish cellular nuclear signal from generalized background. |
| A negative control tissue contains focal positive cells. | HPA's Not detected calls apply to specified cell types, such as lymph-node germinal-center cells, rather than proving every cell in that tissue lacks PKP2 (HPA tissue IHC). | Identify the stained cells before rejecting the control. Compare the exact HPA-listed population and an expected-positive section, then record cell type, compartment and intensity separately. |
Experiment evidence
IHC & IF images showing PKP2 staining
A02146-2 · IHCIHC analysis of PKP2 using anti-PKP2 antibody (A02146-2). PKP2 was detected in a paraffin-embedded section of human lung cancer tissue. Heat
A02146-2 · IHCIHC analysis of PKP2 using anti-PKP2 antibody (A02146-2). PKP2 was detected in a paraffin-embedded section of human colon adenocarcinoma tis
A02146-2 · IFIF analysis of PKP2 using anti-PKP2 antibody (A02146-2) and anti-Beta Tubulin antibody (M01857-3). PKP2 was detected in immunocytochemical s
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000057294-PKP2/tissue/cerebral+cortex#imid_3773552
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000057294-PKP2/tissue/colon#imid_3773478
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000057294-PKP2/tissue/liver#imid_3773479
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000057294-PKP2/tissue/kidney#imid_3773472
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA014314; green = PKP2, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA014314; green = PKP2, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for PKP2 IHC & IF
🧪Run heart muscle first: cardiomyocytes should show PKP2 staining at intercalated disks (HPA: High in cardiomyocytes; UniProt Q99959: intercalated disk localization). Use adipose tissue as the negative tissue (HPA: Not detected in adipocytes); any independently confirmed negative cells within the heart section should lack junctional staining, since the supplied evidence identifies no specific heart cell population as negative.
Positive control tissue: Cerebellum (Processes in granular layer, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show PKP2 in A-431, CACO-2, U2OS, with annotated localisation: Cell Junctions (enhanced) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control, a rabbit host- and clonality-matched isotype control, and a PKP2-knockout biological negative (selected caption: rabbit primary; standard IHC controls). Quench endogenous peroxidase and assess pigment background before scoring heart sections with DAB (selected caption: peroxidase detection with DAB; standard chromogenic IHC practice).
⚠️Feasibility: The catalog antibody has a paraffin-section example using heat retrieval in EDTA at pH 8.0 and primary antibody at 2 μg/ml overnight at 4°C (selected SKU A02146-2 tissue-IHC caption). A target-specific fixation window or fixation effect is unreported, and the selected caption does not state the fixative; its paraffin-section result does not establish fixation (selected SKU A02146-2 tissue-IHC caption). Whether frozen sections or IF are easier is unreported; junctional localization offers an IF/ICC readout (HPA: Cell Junctions enhanced), while endogenous peroxidase or pigment can complicate interpretation of chromogenic heart sections (standard IHC practice). The selected A02146-2 tissue-IHC caption documents paraffin sections, but does not specify the fixative (selected-SKU IHC image A02146-2).
HPA tissue IHC evidence for PKP2
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Cerebellum | Processes in granular layer | High | Protein (IHC) | HPA → |
| Fallopian tube | Ciliated cells (cell body) | High | Protein (IHC) | HPA → |
| Heart muscle | Cardiomyocytes | High | Protein (IHC) | HPA → |
| Nasopharynx | Ciliated cells (ciliary rootlets) | High | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Cervix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Liver | Cholangiocytes | Not detected | Protein (IHC) | HPA → |
| Lymph node | Germinal center cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced PKP2 IHC Tips
Use compartment, cell type, and matched controls to troubleshoot PKP2 staining in paraffin sections (UniProt Q99959; HPA tissue IHC).
How should I adjust retrieval when PKP2 staining is weak in paraffin sections?
Use heat-mediated antigen retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A02146-2). The selected tissue image used this retrieval, followed by 2 µg/ml primary antibody overnight at 4°C, so reproduce those conditions when assessing a weak result (caption A02146-2). If staining remains weak, compare shorter and longer heating intervals on adjacent sections; consider another buffer only as a documented fallback after checking tissue preservation (standard IHC practice). Include a heart muscle section and inspect cardiomyocyte intercalated discs as a positive reference, while recording retrieval conditions for every run (HPA tissue IHC; UniProt Q99959).
Could fixation explain weak or uneven PKP2 staining?
Target-specific fixation sensitivity is unknown because the selected paraffin-section caption does not state a fixative (caption A02146-2). Record fixation and processing history for each specimen, and compare sections with matched handling before attributing a weak chromogenic signal to PKP2 biology (standard IHC practice). Examine poorly preserved regions separately, since damaged morphology makes junctional staining difficult to judge even when the staining run appears technically successful (standard IHC practice; UniProt Q99959 localisation). Use the documented EDTA pH 8.0 retrieval and 2 µg/ml primary condition as starting points, then assess fixation-related variation without claiming a PKP2-specific effect (caption A02146-2).
Where should convincing PKP2 staining appear in tissue?
Prioritise cell junctions and desmosomal plaques when reading chromogenic PKP2 staining; cardiac myocyte intercalated discs are a documented site (UniProt Q99959; HPA tissue IHC). HPA also describes cytoplasmic tissue staining, with high signal in fallopian tube ciliated cell bodies, so a junction-only scoring rule would miss documented patterns (HPA tissue IHC). Nuclear staining can be biologically plausible because UniProt lists the nucleus and HPA supports an additional nucleoplasmic location in cell imaging (UniProt Q99959; HPA subcellular). Compare each compartment with tissue architecture and a matched control before treating diffuse staining as specific, especially where junctions cannot be resolved (standard IHC practice).
How could isoforms or epitope placement affect PKP2 IHC interpretation?
PKP2 has 2 listed isoforms, and the supplied antibody caption does not identify its epitope or establish isoform coverage (UniProt Q99959; caption A02146-2). Therefore, describe staining as antibody-detected PKP2 rather than assigning it to isoform 1 or 2 without epitope documentation or an independent check (UniProt Q99959; standard IHC practice). PKP2 has no annotated transmembrane segment, while annotated modifications include N-terminal phosphoserines and methylarginine; their effects on this antibody’s staining are unknown (UniProt Q99959). If two antibodies give different compartment patterns, compare their documented epitopes and controls before inferring isoform expression or modification-dependent recognition (standard IHC practice).
How can IF help resolve an ambiguous chromogenic PKP2 pattern?
Use IF as a separate follow-up to the paraffin-section IHC result, with a marker identifying the expected cell type and, where useful, a junction marker for spatial comparison (standard IF practice; UniProt Q99959 localisation). For cardiac tissue, assess whether PKP2 signal aligns with cardiomyocyte intercalated discs rather than relying on fluorescence intensity alone (UniProt Q99959; HPA tissue IHC). Choose a fluorophore channel away from prominent tissue autofluorescence, and include single-stain controls to assess bleed-through in the multiplex image (standard IF practice). Because PKP2 lacks a transmembrane segment and occupies junctional and nuclear compartments, compare mild permeabilisation conditions when testing access to an intracellular epitope (UniProt Q99959; standard IF practice).
What should I check when DAB background obscures PKP2 staining?
Start by confirming the documented 10% goat serum block and 2 µg/ml primary concentration before changing several staining variables together (caption A02146-2). The selected image used a peroxidase-conjugated secondary for 30 minutes at 37°C and DAB development, so inspect background at each detection stage (caption A02146-2). Include a primary-omission control, block endogenous peroxidase, and review washing and DAB development time as general chromogenic IHC checks (standard IHC practice). Compare diffuse colour with the expected junctional pattern and with a tissue region lacking documented strong expression before calling low-level background PKP2-positive (UniProt Q99959; HPA tissue IHC; standard IHC practice).
How should I score PKP2 when intensity and junctional distribution vary? ⚠ ANSWER MARKED FOR VERIFICATION
Define the scored cell population and compartment before analysis, then record junctional and nonjunctional staining separately when both are visible (UniProt Q99959 localisation; standard IHC practice). For a cell-based readout, report the percentage of positive target cells and, if intensity is graded, an H-score on a 0–300 scale (standard IHC practice). For discrete junctional signal, quantify positive junction length or stained area relative to the evaluable junction length or tissue area, with the denominator stated explicitly (standard image-analysis practice). Apply the same thresholds, section-quality exclusions, and control reference across cases; HPA reports only medium consistency between antibody staining and RNA expression (standard IHC practice; HPA tissue IHC).
How do I distinguish true PKP2 signal from artefact?
A convincing result follows plausible cells and compartments, such as cardiomyocyte intercalated discs or documented ciliated cell bodies, with preserved tissue architecture (UniProt Q99959; HPA tissue IHC). Treat isolated edge staining, necrotic regions, and widespread colour that also appears in the primary-omission control as artefact candidates (standard IHC practice). Check endogenous peroxidase when DAB signal appears in unexpected cells, and compare those regions with the matched blocked control (standard IHC practice). Interpret disagreements cautiously: HPA rates its tissue staining reliability as Enhanced but reports medium consistency with RNA, while UniProt also lists nuclear and cytoplasmic PKP2 locations (HPA tissue IHC; UniProt Q99959).
Boster reagents
Best PKP2 / Plakophilin-2 IHC Antibodies
A02146-2 has human paraffin-section IHC images and human U2OS cell IF data (catalog image captions); the catalog lists human, mouse and rat reactivity (catalog: reactivity).
Real IHC data
Anti-PKP2 Antibody ®
Cat # A02146-2
A02146-2 will render with its own human lung cancer paraffin-section IHC figure (catalog: IHC image caption). The catalog also documents IHC images from human colon adenocarcinoma, liver cancer and tonsil sections, plus IF in U2OS cells (catalog: image captions).
Which to pick: Choose A02146-2 for paraffin-section IHC: its human lung cancer caption reports EDTA retrieval at pH 8.0 and 2 μg/ml primary antibody (catalog: IHC image caption); the fixative is unreported. For IF/ICC, A02146-2 has a human U2OS cell IF image and a listed concentration of 5 μg/ml (catalog: IF image caption and dilution). For cross-species planning, A02146-2 lists human, mouse and rat reactivity, while its IHC dilution entry specifies human and mouse; the supplied IHC images show human tissue (catalog: reactivity, dilution entry and IHC image captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q99959 (PKP2_HUMAN, Plakophilin-2).
- Human Protein Atlas. PKP2 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. PKP2 subcellular location (ICC-IF): Mainly localized to the cell junctions. In addition localized to the nucleoplasm..
- Human Protein Atlas. PKP2 antibody validation summary (3 antibodies).
- Identification of PKP 2/3 as potential biomarkers of ovarian cancer based on bioinformatics and experiments. Cancer cell international 2020 — PMC7568375.
- Expression of plakophilins (PKP1, PKP2, and PKP3) in gastric cancers. Diagnostic pathology 2011 — PMC3025932.
- Plakophilin-2 Promotes Lung Adenocarcinoma Development via Enhancing Focal Adhesion and Epithelial-Mesenchymal Transition. Cancer management and research 2021 — PMC7837596.
- AAV9:PKP2 improves heart function and survival in a Pkp2-deficient mouse model of arrhythmogenic right ventricular cardiomyopathy. Communications medicine 2024 — PMC10948840.
- PubMed PMID:8922383 — UniProt-cited evidence.
- PubMed PMID:16541075 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for PKP2 (Plakophilin-2). Expected localisation Cytoplasm; cardiac intercalated discs (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A02146-2). Validated IHC antibody: A02146-2 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Cerebellum (Processes in granular layer); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet A02146-2); 2. Fixation: Image fixative and duration unreported (datasheet A02146-2); 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 A02146-2); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A02146-2); 8. Primary antibody: Rabbit anti-PKP2, 2-5 μg/ml (datasheet A02146-2); 9. Primary incubation: Overnight at 4 °C (datasheet A02146-2). Watch for: Fixation: Keep paraffin-section fixation consistent. (standard IHC practice; not target-specific); Caveat: Staining and RNA expression show medium consistency (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope coverage is unspecified (UniProt; datasheet A02146-2); Regulation: Heart muscle–enhanced RNA expression (HPA tissue RNA). Evidence: UniProt Q99959, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the cell junctions. In addition localized to the…, Datasheet A02146-2, PMC7568375, PMC3025932. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/PKP2/immunohistochemistry-ihc-guide.