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PPM1K / Protein phosphatase Mn(2+)-dependent 1K · IHC design guide
Design Immunohistochemistry for PPM1K
Plan PPM1K staining in paraffin sections using the general cytoplasmic tissue pattern as a reference (HPA tissue IHC). Breast glandular cells and ovarian follicle cells show high staining, while liver cholangiocytes are undetected (HPA tissue IHC); start the catalog antibody at 1:100–1:300 (datasheet: IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
PPM1K Immunohistochemistry Experimental Design Guide
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before staining
| Expected localisation | Cytoplasm observed (HPA tissue IHC); mitochondrial matrix expected (UniProt) | |
| Staining pattern | Cytoplasmic staining across tissue cell types (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Breast+4 more · see all | |
| Negative control | Liver |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections. (standard IHC practice; not target-specific) | |
| Caveat | Moderate staining–RNA agreement; verify specificity (HPA tissue IHC) | |
| Regulation | Refeeding raises the BCKDK:PPM1K ratio (UniProt) | |
| Isoform / epitope | 3 isoforms; verify antibody epitope coverage (UniProt) |
Section 1
Recommended PPM1K IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by three published chromogenic PPM1K IHC protocols (PMC12254316; PMC10495377; PMC13066379).
| Sample | Paraffin-embedded human pancreas tissue; fixative not specified (datasheet A04319) |
| Fixation | Image fixative and duration unreported (datasheet A04319); 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-PPM1K, 1:100-1:300 (datasheet A04319) |
| 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 | PPM1K-positive staining in glandular cells of breast (HPA tissue IHC: High). HPA tissue profile: General cytoplasmic expression in all tissues. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 HIER at 95–98 °C for 20 min (page retrieval); compare the published kidney pressure-cooker method (PMC12254316).
Section 2
What Is the Expected PPM1K Staining Pattern?
PPM1K is assigned to the mitochondrial matrix, with cytosolic detection also reported in liver cells (UniProt Q8N3J5: subcellular location). In paraffin tissue sections, expect cytoplasmic staining, including strong staining in breast glandular cells and ovarian follicle cells (HPA: tissue IHC). The protein has no transmembrane segment (UniProt Q8N3J5: topology). HPA rates the tissue staining Approved, with medium agreement with RNA data and external verification pending (HPA: tissue IHC reliability).
| Distinct cytoplasmic chromogen in breast glandular cells or ovarian follicle cells. | This fits the reported High staining in those cells (HPA: tissue IHC). At light microscope resolution, a cytoplasmic pattern is compatible with mitochondrial matrix localisation; the tissue stain alone does not prove mitochondrial identity (UniProt Q8N3J5: subcellular location; HPA: tissue IHC profile). |
| Predominantly nuclear or sharply plasma membrane restricted staining. | Treat this as a compartment mismatch requiring investigation: PPM1K is assigned to the mitochondrial matrix and has no transmembrane segment (UniProt Q8N3J5: subcellular location and topology). Compare with a known positive section and detection controls before calling the pattern specific (general IHC practice). |
| Strong staining of liver cholangiocytes. | HPA reports PPM1K as Not detected in cholangiocytes (HPA: liver tissue IHC). Unexpected signal raises concern for cross-reactivity or endogenous detection activity; it does not establish either cause by itself (general IHC interpretation). Do not treat the whole liver as a negative control. |
| Diffuse chromogen across cells and surrounding tissue, with little cellular distinction. | This does not match the reported general cytoplasmic expression pattern (HPA: tissue IHC profile). Review the no-primary control and staining conditions for background from detection chemistry or excessive antibody signal before scoring individual cells (general IHC practice). |
| No staining in breast glandular cells or ovarian follicle cells. | Both are reported High by HPA, so an entirely blank expected-positive compartment makes this run difficult to interpret (HPA: tissue IHC). Check that the positive control stained and review reagent, retrieval and detection steps (general IHC practice). HPA's Approved rating still has external verification pending (HPA: reliability). |
💡Expected PPM1K appearanceCall a positive result when cytoplasmic chromogen is clear in breast glandular or ovarian follicle cells, where HPA reports High staining; predominant nuclear staining or strong signal in HPA Not detected cholangiocytes warrants investigation (HPA: tissue IHC; UniProt Q8N3J5: subcellular location).
| Tissue and cell selection | Use breast glandular cells and ovarian follicle cells as expected High staining examples; adrenal glandular cells and bronchial respiratory epithelial cells are reported Medium (HPA: tissue IHC). Score the named cell population, since a tissue-wide average can hide a cell-specific mismatch (general IHC practice). |
| Negative comparison | Liver cholangiocytes are reported Not detected, while HPA describes general cytoplasmic expression across tissues (HPA: tissue IHC). They offer a cell-specific comparison, not evidence that every liver cell should be blank. UniProt also reports cytosolic detection in liver cells (UniProt Q8N3J5: subcellular location). |
| Antibody validation | HPA lists IHC as Approved for HPA020862 and HPA023891; its tissue profile has medium agreement with RNA data and awaits external verification (HPA: antibody validation and tissue reliability). Interpret a matching pattern as support for the result, while using controls to assess the particular IHC-validated antibody and run (general IHC practice). |
| Processing and epitope coverage | UniProt lists a processed chain spanning residues 30–372 and three isoforms (UniProt Q8N3J5: processing and isoforms). No antibody epitope is supplied, so coverage of the processed protein or each isoform cannot be inferred. Do not explain a staining difference by epitope loss without antibody-specific evidence. |
| IF/ICC Q: What localisation should an IF image show? | A: HPA reports supported mitochondrial localisation in ICC-IF images from A-431, U-251MG and U2OS (HPA: subcellular ICC-IF). This supports a mitochondrial expectation for IF interpretation, but the ICC-supported antibody HPA020066 has no IHC status listed; its validation does not transfer to an IHC run (HPA: antibody validation). |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected-positive glandular or follicle cells are blank. | The run may have failed to reveal a signal expected to be High in those cells (HPA: tissue IHC); the staining pattern alone does not identify which workflow step failed. | Confirm staining on the positive control, then review the IHC-validated antibody's specified conditions, retrieval and detection reagents in the run record (general IHC practice). |
| Nuclei dominate the stain. | A nuclear dominant pattern conflicts with mitochondrial matrix localisation (UniProt Q8N3J5: subcellular location); nonspecific signal is a possibility, not a diagnosis. | Compare the pattern with breast glandular or ovarian follicle cells and a no-primary control; reassess specificity before scoring nuclei as PPM1K (HPA: tissue IHC; general IHC practice). |
| Liver cholangiocytes stain strongly. | This conflicts with their Not detected HPA result; cross-reactivity or endogenous detection activity could contribute (HPA: liver tissue IHC; general IHC practice). | Compare adjacent liver cell populations, inspect no-primary and detection controls, and record the discrepancy as cell-specific rather than declaring the liver positive or negative as a whole (general IHC practice). |
| Most of the section has diffuse colour. | Broad background obscures the cellular cytoplasmic pattern reported by HPA (HPA: tissue IHC profile). Detection background or overly strong staining can produce this appearance (general IHC practice). | Review the no-primary control, blocking, washing, antibody dilution and chromogen development for this run before assigning cell scores (general IHC practice). |
| A mitochondrial pattern is clear by IF but IHC looks broadly cytoplasmic. | HPA reports supported mitochondrial ICC-IF localisation and a general cytoplasmic tissue IHC profile (HPA: subcellular ICC-IF and tissue IHC). The two image types report localisation at different visual detail. | Judge the paraffin section against the reported cytoplasmic cell pattern; use the IF observation as supporting context, while checking each antibody's application-specific validation (HPA: antibody validation; general IHC practice). |
| Heart muscle is chosen as the sole expected strong protein control. | HPA calls PPM1K RNA tissue enhanced in heart muscle, but that RNA label does not specify a High heart muscle IHC staining level (HPA: RNA specificity and tissue IHC). | Include a reported High IHC cell population, such as breast glandular or ovarian follicle cells, when assessing whether the stain worked (HPA: tissue IHC). |
Experiment evidence
IHC & IF images showing PPM1K staining
A04319 · IHCImmunohistochemistry analysis of paraffin-embedded human pancreas tissue, using PPM1K Antibody. The picture on the right is blocked with the
A04319-1 · IHCImmunohistochemistry analysis of paraffin-embedded human pancreas tissue, using PPM1K Antibody. The picture on the right is blocked with the
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000163644-PPM1K/tissue/cerebral+cortex#imid_6183512
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000163644-PPM1K/tissue/colon#imid_6181142
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000163644-PPM1K/tissue/liver#imid_6181143
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000163644-PPM1K/tissue/kidney#imid_6181136
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA020066; green = PPM1K, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA020066; green = PPM1K, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for PPM1K IHC & IF
🧪Run breast first and score its glandular cells, where PPM1K staining is High (HPA: Breast, glandular cells High). Run liver and score cholangiocytes as the negative tissue (HPA: Liver, cholangiocytes Not detected); on the breast slide, use adjacent nonglandular areas to assess background without assuming those cells are PPM1K-negative (HPA: Breast lists glandular cells as High).
Positive control tissue: Breast (Glandular cells, HPA High)
Negative control tissue: Liver (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show PPM1K in A-431, U-251MG, U2OS, with annotated localisation: Mitochondria (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a nonimmune isotype control matched to the primary antibody’s host species and clonality; use PPM1K knockout material or peptide blocking as a biological specificity control (standard IHC practice; selected A04319 tissue-IHC caption: peptide block). For chromogenic breast sections, quench endogenous peroxidase and check tissue background before scoring glandular staining (standard IHC practice).
⚠️Feasibility: A target-specific fixation window and antigen-retrieval dependency are unreported in the supplied evidence; the selected A04319 paraffin-section caption does not report a fixative (selected A04319 tissue-IHC caption). The evidence does not establish whether frozen sections or IF are easier than paraffin IHC, although mitochondrial ICC-IF localization is supported in A-431, U-251MG and U2OS cells (HPA: subcellular). No breast-specific staining artefact is documented in the supplied evidence; assess glandular staining against the controls and adjacent tissue background (HPA: Breast, glandular cells High; standard IHC practice).
HPA tissue IHC evidence for PPM1K
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Medium consistency between antibody staining and RNA expression data. Pending external verification.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Breast | Glandular cells | High | Protein (IHC) | HPA → |
| Ovary | Follicle cells | High | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | Medium | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Medium | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Liver | Cholangiocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced PPM1K IHC Tips
Troubleshoot PPM1K staining in paraffin sections by checking retrieval, controls and the expected cellular pattern before comparing signal across samples.
What should I change when PPM1K staining is weak after antigen retrieval?
Start with citrate buffer at pH 6.0, heated to 95–98 °C for 20 min (page retrieval setting). Let sections cool in buffer before washing, and compare slides processed in the same run so retrieval differences do not masquerade as biological differences (standard IHC practice). If staining remains weak, test a second retrieval condition on adjacent sections while holding antibody dilution and detection constant (standard IHC practice). Judge improvement by cellular staining and background together: PPM1K is mainly mitochondrial (UniProt Q8N3J5 localisation; HPA subcellular), while the selected pancreas image establishes staining in paraffin sections without reporting its retrieval method (A04319 caption).
How can I troubleshoot weak staining when the section fixative is uncertain?
Treat PPM1K’s fixation sensitivity as unknown: the selected pancreas caption identifies paraffin sections but does not state a fixative (A04319 caption). Record the fixative and processing history for each block, then compare sections of the same thickness stained in one run (standard IHC practice). For prospective specimens, use a consistent fixation schedule and examine morphology alongside signal; a change in staining alone cannot establish a PPM1K-specific fixation effect (standard IHC practice). Keep retrieval and detection settings matched during that comparison, and interpret any shift cautiously because the available tissue image supplies no fixation comparison (A04319 caption).
Does diffuse cytoplasmic PPM1K staining fit its expected localisation?
Expect cytoplasmic staining that may resolve into a granular mitochondrial pattern: PPM1K is assigned to the mitochondrial matrix, and mitochondrial localisation is supported by ICC/IF (UniProt Q8N3J5 localisation; HPA subcellular). General cytoplasmic tissue staining is also reported, so chromogenic resolution may not reveal individual mitochondria (HPA tissue IHC profile; standard IHC practice). Compare the suspect section with a mitochondrial marker on an adjacent section and inspect intact cells at higher magnification (standard IHC practice). Diffuse staining alone is not proof of mislocalisation, especially because cytosolic detection in liver cells is noted in the protein record (UniProt Q8N3J5 localisation).
Could an isoform or hidden epitope explain discordant PPM1K staining?
PPM1K has 3 annotated isoforms, but the supplied product caption does not identify the antibody epitope or establish isoform coverage (UniProt Q8N3J5 isoforms; A04319 caption). The annotated processed chain spans residues 30–372, the PPM-type domain spans 94–346, and Ser-248 is a reported modified residue (UniProt Q8N3J5 processing, domain and modified residues). These annotations guide questions about epitope accessibility; they do not show that fixation or phosphorylation changes this antibody’s binding (standard IHC interpretation). If staining conflicts with another assay, obtain the immunogen sequence and compare it with each isoform before attributing the discrepancy to splicing (standard IHC practice).
How should I adapt this PPM1K assessment to multiplex IF?
Use the separate IF/ICC workflow to pair PPM1K with a marker for the expected cell population, such as glandular cells in breast or follicle cells in ovary (HPA tissue IHC: High in those cells; standard IF practice). Choose spectrally separated fluorophores and consider a far-red PPM1K channel when tissue autofluorescence obscures shorter wavelengths (standard IF practice). Because PPM1K is assigned to the mitochondrial matrix and has no transmembrane segment, optimise permeabilisation for access through mitochondrial membranes while checking organelle morphology (UniProt Q8N3J5 topology and localisation; standard IF practice). Include single-stain and no-primary controls to identify bleed-through and background before calling colocalisation (standard IF practice).
How can I distinguish PPM1K staining from chromogenic background?
Run a no-primary section and inspect whether colour persists in the same structures; residual colour implicates the detection workflow rather than primary-antibody binding (standard IHC practice). For peroxidase-based detection, include an endogenous-peroxidase block and keep DAB development time consistent across slides (standard IHC practice). Titrate the primary antibody and check blocking and wash steps if colour spreads beyond intact cellular cytoplasm (standard IHC practice; HPA tissue IHC profile). The selected pancreas image includes a peptide-blocked comparator, which supports testing antibody-dependent signal in that image but does not establish specificity in every tissue (A04319 caption).
What should I score when comparing PPM1K across tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population before scoring: HPA reports high staining in breast glandular cells and ovary follicle cells, but no detection in liver cholangiocytes (HPA tissue IHC). Within that population, report the percentage of positive cells and staining intensity, or calculate an H-score from intensity categories; keep thresholds fixed across the batch (standard IHC practice). Normalise positive-cell counts to the number of evaluable cells, or staining density to analysed tissue area in mm², and exclude folds and necrosis (standard IHC practice). Record retrieval and detection batch because the HPA tissue assessment has medium staining–RNA consistency and awaits external verification (HPA tissue IHC reliability).
Which PPM1K staining patterns should make me suspect artefact?
Give greatest weight to staining in intact cellular cytoplasm that fits a mitochondrial protein, while recognising that the chromogenic pattern may appear diffuse (UniProt Q8N3J5 localisation; HPA subcellular; HPA tissue IHC profile). Reconsider a claim based on isolated nuclear colour, stained necrotic debris, or signal concentrated only at section edges (UniProt Q8N3J5 localisation; standard IHC practice). Check cell identity as well: HPA reports no detectable signal in liver cholangiocytes, though that observation alone is not a universal negative control (HPA tissue IHC). Persistent colour on a no-primary slide, particularly with peroxidase detection, points to background that needs control before biological interpretation (standard IHC practice).
Boster reagents
Best PPM1K / Protein phosphatase Mn(2+)-dependent 1K IHC Antibodies
Both anti-PPM1K antibodies have human pancreas paraffin-section IHC images (catalog image captions) and list IF plus Human, Mouse and Rat reactivity (catalog applications and reactivity); no IF image is supplied (catalog image fields).
Real IHC data
Anti-PP2C kappa PPM1K Antibody
Cat # A04319
Real IHC data
Anti-PPM1K/Pp2C Kappa Antibody
Cat # A04319-1
A04319 lists IHC and IF for Human, Mouse and Rat (catalog applications and reactivity), with an IHC image of paraffin-embedded human pancreas tissue and peptide blocking (A04319 image caption). A04319-1 also lists ICC (catalog applications) and has its own IHC image of paraffin-embedded human pancreas tissue with peptide blocking (A04319-1 image caption).
Which to pick: For tissue IHC, either SKU has its own paraffin-section human pancreas example (A04319 image caption; A04319-1 image caption); the fixative is unreported in both captions. For ICC, choose A04319-1 because ICC is listed for that SKU (A04319-1 applications); for IF, both list IF, with no IF image supplied for either (catalog applications and image fields). For Human, Mouse or Rat samples, both list reactivity in those species (catalog reactivity), while the supplied IHC images document human pancreas only (A04319 image caption; A04319-1 image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q8N3J5 (PPM1K_HUMAN, Protein phosphatase Mn(2+)-dependent 1K).
- Human Protein Atlas. PPM1K tissue IHC expression (reliability: Approved).
- Human Protein Atlas. PPM1K subcellular location (ICC-IF): Localized to the mitochondria..
- Human Protein Atlas. PPM1K antibody validation summary (3 antibodies).
- Loss of p300 in proximal tubular cells reduces renal fibrosis and endothelial-mesenchymal transition. EMBO molecular medicine 2025 — PMC12254316.
- The amino acid metabolomics signature of differentiating myocardial infarction from strangulation death in mice models. Scientific reports 2023 — PMC10495377.
- Branched-chain α-keto acids impair glucose-stimulated insulin secretion in pancreatic β-cells under diabetes by reactivating the LDHA-lactate axis. Nature communications 2026 — PMC13066379.
- PPM1K mediates metabolic disorder of branched-chain amino acid and regulates cerebral ischemia-reperfusion injury by activating ferroptosis in neurons. Cell death & disease 2023 — PMC10522625.
- PubMed PMID:17374715 — UniProt-cited evidence.
- PubMed PMID:17336929 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for PPM1K (Protein phosphatase Mn(2+)-dependent 1K). Expected localisation Cytoplasm observed (HPA tissue IHC); mitochondrial matrix expected (UniProt). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: A04319 at 1:100-1:300 (the product's own IHC validation image is shown). Controls (HPA): positive Breast (Glandular cells); negative Liver. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human pancreas tissue; fixative not specified (datasheet A04319); 2. Fixation: Image fixative and duration unreported (datasheet A04319); 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-PPM1K, 1:100-1:300 (datasheet A04319); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Moderate staining–RNA agreement; verify specificity (HPA tissue IHC); Isoform / epitope: 3 isoforms; verify antibody epitope coverage (UniProt); Regulation: Refeeding raises the BCKDK:PPM1K ratio (UniProt). Evidence: UniProt Q8N3J5, HPA tissue IHC · Approved, HPA ICC-IF · mitochondria., Datasheet A04319, PMC12254316, PMC10495377. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/PPM1K/immunohistochemistry-ihc-guide.