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KCNJ2 / Inward rectifier potassium channel 2 · IHC design guide
Design Immunohistochemistry for KCNJ2
Plan paraffin-section KCNJ2 IHC with tissue controls, antibody titration, and scoring. Compare the cytoplasmic tissue staining (HPA tissue IHC) with the channel’s annotated membrane location (UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
KCNJ2 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 | Diffuse cytoplasm (HPA tissue IHC); cell membrane (UniProt) | |
| Staining pattern | Cytoplasmic staining in most tissues (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | None in HPA (detected in all 45 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep formalin fixation consistent across sections (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 A01850-1) | |
| Caveat | Staining has low consistency with RNA expression (HPA tissue IHC) | |
| Regulation | No expression regulator reported (UniProt) | |
| Isoform / epitope | No annotated isoforms; cytoplasmic and extracellular regions (UniProt) |
Section 1
Recommended KCNJ2 IHC & IF Protocols
The catalog antibody’s IHC-P protocol is followed by published KCNJ2 IHC methods for osteosarcoma and lung sections (PMC9979522; PMC13205818).
| Sample | Paraffin-embedded human breast carcinoma tissue; fixative not specified (datasheet A01850-1) |
| Fixation | Image fixative and duration unreported (datasheet A01850-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in citrate buffer, pH 6.0, 20 min at 95–98 °C (standard rule: cytoplasmic / membrane antigen) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Rabbit anti-KCNJ2, 1:50-1:200 (datasheet A01850-1) |
| Primary incubation | Overnight at 4 °C (standard) |
| Detection | HRP-polymer secondary, DAB chromogen 5–10 min (standard) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | KCNJ2-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page antigen retrieval); both published methods used citrate (PMC9979522; PMC13205818).
Section 2
What Is the Expected KCNJ2 Staining Pattern?
KCNJ2 is a cell membrane channel with cytoplasmic and extracellular regions (UniProt P63252 topology). In IHC, expect staining in cells such as cerebellar Purkinje cells, cortical neurons and bronchial respiratory epithelial cells (HPA: High). HPA also reports cytoplasmic expression in most tissues (HPA: tissue profile). Its IHC antibody is Approved, with low consistency between staining and RNA expression (HPA: reliability).
| Defined staining in Purkinje cells or bronchial respiratory epithelium, with a membrane-associated pattern. | These are useful positive-pattern examples (HPA: High in both cell types). Membrane staining fits KCNJ2 localisation (UniProt P63252: cell membrane). Judge the cell type and compartment together; HPA also describes cytoplasmic staining in most tissues (HPA: tissue profile). |
| Strong, isolated nuclear staining with little staining at the cell edge or in the cytoplasm. | A nuclear-only pattern conflicts with the recorded membrane localisation (UniProt P63252: cell membrane; HPA: subcellular summary, Membrane). Treat it as suspect staining and assess controls before assigning it to KCNJ2 (general IHC practice). |
| Strong staining in unexpected cells while the expected cells on the same section remain faint. | Review cell identification and antibody specificity; cross-reactivity or endogenous detection activity are possibilities, not established causes (general IHC practice). HPA names particular High-staining cell populations but also reports cytoplasmic staining in most tissues, so an unlisted cell is not automatically negative (HPA: tissue profile). |
| Broad, nearly uniform colour across unrelated structures or outside identifiable cells. | The result lacks the cell-specific contrast needed to interpret an IHC stain (general IHC practice). Diffuse background cannot establish KCNJ2 localisation, even though HPA reports cytoplasmic expression across most tissues (HPA: tissue profile). Compare with an appropriate detection control (general IHC practice). |
| No convincing signal in a section containing identifiable Purkinje cells or cortical neurons. | Both populations have High HPA tissue staining, so the result calls for a run-level check (HPA: High in cerebellar Purkinje cells and cerebral-cortex neurons). Absence on one slide does not establish biological absence; verify tissue identification, antibody conditions and detection controls (general IHC practice). |
💡Expected KCNJ2 appearanceA convincing positive result is cell-associated, preferably membrane-associated staining in a High-staining population such as Purkinje cells, whereas isolated nuclear colour or uniform background is suspect (UniProt P63252: cell membrane; HPA: High in Purkinje cells; general IHC practice).
| Compartment and topology | KCNJ2 has two transmembrane segments and substantial cytoplasmic regions (UniProt P63252 topology). A membrane-associated result fits the annotated location (UniProt P63252: cell membrane); HPA's predominantly cytoplasmic tissue IHC profile creates an interpretation caveat rather than proof that every cytoplasmic signal is specific (HPA: tissue profile). |
| Choice of tissue and cell population | HPA reports High staining in several defined populations, including Purkinje cells, cortical neurons, respiratory epithelial cells and colon endothelial cells (HPA: tissue IHC). Adipocytes are listed as Low, not negative (HPA: adipose tissue). Use the identified cell population when assessing a section; whole-tissue staining can conceal that distinction (general IHC practice). |
| Strength of the HPA IHC evidence | The listed antibody, HPA029109, has Approved IHC status; its record does not state Enhanced IHC status (HPA: antibody validation). HPA explicitly reports low consistency between staining and RNA expression (HPA: reliability description). Interpret a plausible pattern with that qualification, especially when using RNA abundance as a comparison. |
| Protein processing and epitope interpretation | The supplied UniProt record lists one chain spanning residues 1–427, with no signal peptide, propeptide or annotated isoforms (UniProt P63252: processing and isoforms). It does not identify this antibody's epitope, so topology alone cannot determine whether retrieval or permeabilisation will expose it in a paraffin section (UniProt P63252 topology; general IHC practice). |
| IF/ICC cross-check — what pattern is documented? | HPA summarises KCNJ2's subcellular location as Membrane, but supplies no ICC-IF image-bearing cell lines or main-location entry here (HPA: subcellular record). This supports a location expectation, not an image-based IF validation or an IF/ICC protocol choice. |
| Situation | Likely cause | Next action |
|---|---|---|
| A known High-staining cell population is blank. | A failed stain or detection step is possible; absence alone does not identify the cause (HPA: High in Purkinje cells and cortical neurons; general IHC practice). | Check that the expected cells are present, then review the run's antibody and detection controls and the documented IHC-P conditions (general IHC practice). |
| The slide shows nuclear-only staining. | The compartment conflicts with KCNJ2's membrane annotation and HPA's Membrane summary (UniProt P63252: cell membrane; HPA: subcellular record). | Compare the same run with a defined High-staining cell population and a detection control before interpreting the nuclear signal (HPA: tissue IHC; general IHC practice). |
| Colour is widespread and cell boundaries are hard to distinguish. | Background or excess detection signal may obscure cell-level interpretation (general IHC practice). HPA's broad cytoplasmic profile alone does not validate uniform slide-wide colour (HPA: tissue profile). | Assess detection-control staining and adjust general IHC blocking, washing or detection conditions as indicated by the controls (general IHC practice). |
| Unexpected cells stain more strongly than the named High-staining population. | Cell misidentification, cross-reactivity or endogenous detection activity are possible explanations (general IHC practice); HPA does not designate all other cells negative (HPA: tissue profile). | Recheck morphology and compare an appropriate detection control with the expected cells on the same section (general IHC practice). |
| Cytoplasmic staining appears without a crisp membrane outline. | HPA reports cytoplasmic expression in most tissues, while UniProt places KCNJ2 at the membrane (HPA: tissue profile; UniProt P63252: cell membrane). The records do not resolve every cytoplasmic signal's specificity. | Record the observed compartment precisely; weigh its cell distribution and controls before calling it KCNJ2-specific (general IHC practice). |
| Adipocytes show weak staining, or staining differs from an RNA-based expectation. | HPA lists adipocytes as Low and reports low consistency between antibody staining and RNA expression (HPA: adipose tissue; HPA: reliability description). | Treat Low as a comparison level rather than a zero-signal control, and report the IHC observation separately from RNA evidence (HPA: adipose tissue and reliability; general IHC practice). |
Experiment evidence
IHC & IF images showing KCNJ2 staining
A01850-1 · IHCImmunohistochemistry (IHC) analyzes of KIR2.1 (C122) pAb in paraffin-embedded human breast carcinoma tissue at 1:50.
A30730 · IHCImmunohistochemistry analysis of paraffin-embedded human brain tissue, using KCNJ2 Antibody. The picture on the right is blocked with the sy
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000123700-KCNJ2/tissue/cerebral+cortex#imid_7754672
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000123700-KCNJ2/tissue/colon#imid_7754598
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000123700-KCNJ2/tissue/liver#imid_7754591
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000123700-KCNJ2/tissue/kidney#imid_7754600
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for KCNJ2 IHC & IF
🧪Run breast first and assess staining in glandular cells (High; HPA: breast glandular cells), consistent with the selected IHC caption showing staining in paraffin-embedded human breast carcinoma (caption: A01850-1). HPA detects KCNJ2 in all 45 scored tissues, so there is no HPA negative tissue; use no-primary and isotype controls, and expect cells outside the stained glandular population on the same slide to show background-level signal without assuming they are biologically KCNJ2-negative (HPA: no negative rows; standard IHC control practice).
Positive control tissue: Adrenal gland (Glandular cells, HPA High)
Negative control tissue: None in HPA: KCNJ2 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for KCNJ2; 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-species- and immunoglobulin-class-matched isotype or normal-IgG control appropriate to the primary antibody's clonality; a matched KCNJ2 knockout sample can test target specificity (standard IHC control practice). For chromogenic breast IHC, quench endogenous peroxidase and check any biotin-based detection system for endogenous biotin background (standard IHC practice).
⚠️Feasibility: A target-specific fixation window, fixation effect, and retrieval dependency are unreported in the supplied evidence; the selected paraffin-section caption gives 1:50 but does not state a fixative (caption: A01850-1). Optimize antigen retrieval empirically for paraffin sections and assess membrane-associated signal against background (UniProt P63252: cell-membrane localisation; standard IHC practice). The evidence does not establish that frozen sections or IF are easier for KCNJ2; endogenous peroxidase can complicate chromogenic interpretation in the selected breast tissue (standard IHC practice).
HPA tissue IHC evidence for KCNJ2
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Low consistency between antibody staining and RNA expression data.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | High | Protein (IHC) | HPA → |
| Breast | Glandular cells | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Caudate | Neuronal cells | High | Protein (IHC) | HPA → |
| Cerebellum | Purkinje cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: KCNJ2 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced KCNJ2 IHC Tips
Troubleshoot KCNJ2 staining in paraffin sections by checking retrieval, compartment, cell identity and controls before interpreting chromogenic signal.
How should I adjust retrieval when KCNJ2 staining is weak or uneven?
Use citrate pH 6.0 heat-induced retrieval at 95–98 °C for 20 min on paraffin sections (page retrieval rule). If staining is weak, first confirm that sections reached the stated temperature throughout the run, then compare a modestly longer heating time on adjacent sections while keeping citrate pH 6.0 constant (standard IHC practice). Record section thickness, cooling time and staining batch so a stronger signal can be distinguished from run variation (standard IHC practice). Judge improvement by expected sarcolemmal or cell membrane staining alongside background, since KCNJ2 is annotated at those sites (UniProt P63252 localisation).
Could fixation explain variable KCNJ2 staining between paraffin blocks?
The supplied KCNJ2 tissue caption reports a paraffin-embedded section but does not state its fixative, so target-specific fixation sensitivity is unknown (A01850-1 caption). Compare blocks with documented fixation histories using the same section thickness, citrate pH 6.0 retrieval and detection run (page retrieval rule; standard IHC practice). Include a previously staining control section in each run, and examine preservation and background before attributing a difference to antigen loss (standard IHC practice). Record fixative and fixation duration for future specimens; neither the reported tissue staining pattern nor KCNJ2 topology establishes a fixation optimum (HPA tissue IHC; UniProt P63252 topology).
How do I evaluate cytoplasmic staining for a membrane channel?
KCNJ2 is annotated at the cell membrane, sarcolemma and T-tubule, with cytoplasmic regions at residues 1–81 and 179–427 (UniProt P63252 localisation and topology). HPA nevertheless reports cytoplasmic expression in most tissues and rates its tissue IHC Approved with low consistency between staining and RNA data (HPA tissue IHC). Score crisp membrane-associated staining separately from diffuse cytoplasmic signal, using the same compartment definitions across sections (standard IHC practice). Compare neighbouring cells and a no-primary control before calling cytoplasmic staining specific; the reported HPA pattern alone does not resolve that distinction (HPA tissue IHC; standard IHC practice).
How does epitope position affect KCNJ2 staining in paraffin sections?
The supplied record lists 0 isoforms and one chain spanning residues 1–427, so it provides no isoform-specific staining interpretation (UniProt P63252 processing and isoforms). KCNJ2 has transmembrane segments at 82–106 and 157–178, with extracellular regions at 107–128 and 148–156 (UniProt P63252 topology). Check the catalog antibody’s documented immunogen before deciding whether its epitope is cytoplasmic or extracellular; that location is not supplied in the payload (catalog antibody information supplied). If staining changes after retrieval, compare adjacent sections under matched detection conditions rather than assigning the change to an isoform or epitope alteration without evidence (standard IHC practice).
What should I check when adapting the KCNJ2 question to multiplex IF?
On the separate IF/ICC guide, pair KCNJ2 with a validated marker for the expected cell type and assess whether signals occupy the same cells and plausible compartments (standard IF practice; UniProt P63252 localisation). Choose fluorophores after inspecting unstained tissue autofluorescence, favouring channels with clear separation from that background and from each other (standard IF practice). Set permeabilisation according to the documented antibody epitope: intracellular regions may require access, whereas extracellular epitopes warrant a comparison without permeabilisation (UniProt P63252 topology; standard IF practice). The paraffin-section caption documents IHC at 1:50, not an IF dilution or fixation condition (A01850-1 caption).
What causes diffuse brown signal around KCNJ2-positive structures?
Compare a no-primary section and the full staining run to identify detection-system background before changing the KCNJ2 antibody concentration (standard chromogenic IHC practice). Apply the routine peroxidase block before chromogenic detection, and check whether endogenous enzyme activity or pigment remains visible in controls (standard chromogenic IHC practice). Titrate the primary antibody around the caption’s 1:50 starting point on matched sections, recording incubation and wash conditions for each run (A01850-1 caption; standard IHC practice). Prefer a condition that preserves defined cell membrane or sarcolemmal staining over one that increases diffuse brown deposition, consistent with annotated KCNJ2 localisation (UniProt P63252 localisation; standard IHC practice).
How should I score KCNJ2 IHC across heterogeneous fields? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and membrane versus cytoplasmic compartment before scoring, because KCNJ2 is membrane-associated while HPA also reports cytoplasmic tissue staining (UniProt P63252 localisation; HPA tissue IHC). For a chosen compartment, record percent positive cells and staining intensity, then calculate an H-score as the sum of each intensity grade multiplied by its percent of cells (standard IHC practice). If measuring stained area, report it per mm² of evaluable tissue or per counted target cells, excluding folds and necrosis by a prespecified rule (standard IHC practice). Keep exposure, threshold and scoring rules fixed across sections, and report membrane and cytoplasmic results separately (standard IHC practice).
When is a KCNJ2-positive field convincing rather than artefactual?
A convincing result has reproducible staining in identifiable cells, with membrane-associated signal consistent with KCNJ2 localisation and an appropriately quiet no-primary control (UniProt P63252 localisation; standard IHC practice). HPA reports high staining in breast glandular cells and several other listed cell populations, but also flags low consistency between staining and RNA data (HPA tissue IHC). Treat signal limited to section edges, folds or necrotic regions as suspect, and check endogenous peroxidase activity when brown staining persists in controls (standard chromogenic IHC practice). Do not assign diffuse nuclear staining to KCNJ2 on these data; its supplied localisation is membrane, sarcolemma and T-tubule (UniProt P63252 localisation).
Boster reagents
Best KCNJ2 / Inward rectifier potassium channel 2 IHC Antibodies
Two anti-KCNJ2 antibodies have IHC images from paraffin-embedded human breast carcinoma and brain tissue (catalog image captions); A30730 also lists IF/ICC applications (catalog applications).
Real IHC data
Anti-KIR2.1 (C122) KCNJ2 Antibody
Cat # A01850-1
Real IHC data
Anti-KCNJ2/Kir2.1 Antibody
Cat # A30730
A01850-1 shows IHC staining of paraffin-embedded human breast carcinoma at 1:50 and lists Human, Mouse, and Rat reactivity (A01850-1 image caption; catalog reactivity). A30730 shows IHC staining of paraffin-embedded human brain tissue with a peptide-blocked comparison and lists Human and Rat reactivity plus IF/ICC applications (A30730 image caption; catalog applications/reactivity).
Which to pick: For tissue IHC, choose A01850-1 for paraffin-embedded breast carcinoma or A30730 for paraffin-embedded brain tissue, matching each antibody’s own image (catalog image captions). For IF/ICC, choose A30730 because those applications are listed, although no IF image is supplied (A30730 catalog applications; IF image data). For mouse samples, A01850-1 lists Mouse reactivity; both IHC captions describe paraffin-embedded tissue without reporting the fixative (catalog reactivity; catalog image captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P63252 (KCNJ2_HUMAN, Inward rectifier potassium channel 2).
- Human Protein Atlas. KCNJ2 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. KCNJ2 subcellular location (ICC-IF): Membrane.
- Human Protein Atlas. KCNJ2 antibody validation summary (1 antibodies).
- KCNJ2/HIF1α positive-feedback loop promotes the metastasis of osteosarcoma. Cell communication and signaling : CCS 2023 — PMC9979522.
- KCNJ2 is Required for NLRP3 Inflammasome Activation That Drives Allergic Airway Inflammation and Remodeling. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 2026 — PMC13205818.
- Upregulation of the inwardly rectifying potassium channel Kir2.1 (KCNJ2) modulates multidrug resistance of small-cell lung cancer under the regulation of miR-7 and the Ras/MAPK pathway. Molecular cancer 2015 — PMC4373128.
- Soluble epoxide hydrolase inhibitors, t-AUCB, regulated microRNA-1 and its target genes in myocardial infarction mice. Oncotarget 2017 — PMC5706901.
- PubMed PMID:7696590 — UniProt-cited evidence.
- PubMed PMID:7590287 — UniProt-cited evidence.
- PubMed PMID:8821791 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for KCNJ2 (Inward rectifier potassium channel 2). Expected localisation Diffuse cytoplasm (HPA tissue IHC); cell membrane (UniProt). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: A01850-1 at 1:50-1:200 (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative None in HPA (detected in all 45 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human breast carcinoma tissue; fixative not specified (datasheet A01850-1); 2. Fixation: Image fixative and duration unreported (datasheet A01850-1); 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-induced epitope retrieval in citrate buffer, pH 6.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-KCNJ2, 1:50-1:200 (datasheet A01850-1); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep formalin fixation consistent across sections (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 A01850-1); Caveat: Staining has low consistency with RNA expression (HPA tissue IHC); Isoform / epitope: No annotated isoforms; cytoplasmic and extracellular regions (UniProt); Regulation: No expression regulator reported (UniProt). Evidence: UniProt P63252, HPA tissue IHC · Approved, HPA ICC-IF · Membrane, Datasheet A01850-1, PMC9979522, PMC13205818. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/KCNJ2/immunohistochemistry-ihc-guide.