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AKAP4 / A-kinase anchor protein 4 · IHC design guide
Design Immunohistochemistry for AKAP4
Plan chromogenic AKAP4 IHC in paraffin sections using testis as a positive control: staining is high in elongated or late spermatids (HPA tissue IHC). This guide covers consistent fixation, the catalog antibody’s 5 μg/mL starting concentration (datasheet), and the expected sperm flagellar location (UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
AKAP4 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 | Sperm flagellar principal piece expected (UniProt) | |
| Staining pattern | Selective elongated or late spermatid staining; compartment unreported (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Testis | |
| 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 | Reported spermatid stage differs between sources (UniProt; HPA tissue IHC) | |
| Regulation | Spermatid-restricted expression (UniProt) | |
| Isoform / epitope | 2 isoforms; mature chain 189–854; epitope unknown (UniProt) |
Section 1
Recommended AKAP4 IHC & IF Protocols
The catalog antibody IHC-P protocol is accompanied by published AKAP4 IHC protocols for ovarian carcinoma, testis, breast cancer, and lung cancer samples (PMC3667910; PMC5462453; PMC3579772; PMC8974088).
| Sample | Tissue sections; selected-image fixative not specified (standard IHC workflow) |
| Fixation | Image fixative and duration unreported (datasheet A07362); 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-AKAP4, 5 μg/mL (datasheet A07362) |
| 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 | AKAP4-positive staining in elongated or late spermatids of testis (HPA tissue IHC: High). HPA tissue profile: Selective expression in spermatids of seminiferous ducts. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page retrieval); the testis protocol also uses citrate pH 6.0 (PMC5462453).
Section 2
What Is the Expected AKAP4 Staining Pattern?
AKAP4 should stain spermatids in testis, with signal associated with the developing sperm flagellum (HPA tissue IHC: selective spermatid staining; UniProt Q5JQC9: sperm flagellum). HPA reports high staining in elongated or late spermatids and rates the tissue pattern Enhanced because staining agrees with RNA expression (HPA tissue IHC). AKAP4 has no transmembrane segment (UniProt Q5JQC9 topology).
| Strong staining in elongated or late spermatids within seminiferous ducts, concentrated along flagellar structures. | This fits the observed high testis staining (HPA tissue IHC) and the principal-piece location of AKAP4 (UniProt Q5JQC9; HPA subcellular). Judge localisation alongside cell identity: flagellar staining without the expected spermatid context needs closer review. |
| Predominantly nuclear, broadly membranous, or diffuse somatic-cell staining instead of a spermatid-associated flagellar pattern. | These compartments do not match the reported principal-piece location (HPA subcellular; UniProt Q5JQC9). Treat the pattern as a possible specificity or detection artefact; inspect morphology and controls before scoring it as AKAP4-positive. |
| Staining in many nonspermatid cells, or convincing staining in a tissue listed as negative. | Broad staining conflicts with selective spermatid expression (HPA tissue IHC). Adipocytes in adipose tissue and glandular cells in adrenal gland are reported not detected (HPA tissue IHC). Check for cross-reactivity or endogenous detection activity using suitable controls (general IHC practice). |
| Diffuse colour across tissue, lumina, and background, with little distinction between cells or compartments. | A diffuse deposit cannot establish the selective spermatid pattern (HPA tissue IHC). Evaluate a no-primary control, blocking, washing, and chromogen development (general IHC practice). Background alone does not identify which step caused the signal. |
| No staining in morphologically identifiable late spermatids in a testis section. | This misses a reported high positive population (HPA tissue IHC). Confirm the relevant cell stage is present, then review antibody suitability, retrieval, dilution, detection reagents, and control performance (general IHC practice). A negative slide alone does not establish absent AKAP4. |
💡Expected AKAP4 appearanceCall positive when high signal is restricted to elongated or late spermatids and follows their flagellar principal-piece region (HPA tissue IHC; HPA subcellular); widespread nuclear or somatic-cell colour is suspect against that reference pattern.
| Cell stage | HPA observes selective staining in elongated or late spermatids, whereas UniProt describes expression in round spermatids (HPA tissue IHC; UniProt Q5JQC9 tissue specificity). Record the stage actually visible rather than treating the two annotations as identical. |
| Subcellular position | The principal piece is the reported location in sperm, consistent with AKAP4 being a major fibrous-sheath component (HPA subcellular; UniProt Q5JQC9 function). Cell identity and compartment together make the stronger interpretation. |
| Protein processing and isoforms | UniProt lists a precursor with residues 1–188 annotated as propeptide, a 189–854 chain, and 2 isoforms (UniProt Q5JQC9 processing; isoforms). The supplied sources do not map an antibody epitope, so they cannot predict which form a given stain detects. |
| Antibody validation | Both listed antibodies, HPA005949 and HPA020046, have Enhanced IHC status (HPA antibodies). HPA reports high agreement between staining and RNA expression for the tissue pattern (HPA tissue IHC); this supports the reference pattern without proving every deposit specific. |
| IF/ICC Q: Where should sperm signal localise? | A: To the principal piece (HPA subcellular: enhanced). This provides a localisation cross-check for interpreting IHC; the supplied IF/ICC evidence does not specify an IHC-P retrieval or detection setting. |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected testis positive is blank. | The section may lack identifiable elongated or late spermatids, the high population in HPA tissue IHC; a technical failure is also possible (general IHC practice). | Verify spermatid stages on the section, then check the positive control, antibody dilution, retrieval, and detection sequence (general IHC practice). Do not infer target-specific retrieval sensitivity from HPA. |
| Staining appears in most cell types. | That distribution conflicts with selective spermatid staining (HPA tissue IHC). Nonspecific binding or endogenous detection activity are possible causes (general IHC practice). | Compare a no-primary control; review blocking and detection controls, then assess whether spermatid staining remains distinct (general IHC practice). |
| Signal is mainly nuclear or broadly membranous. | That location conflicts with the principal-piece reference (HPA subcellular; UniProt Q5JQC9 location). | Recheck cell and flagellar morphology, inspect controls, and score the discordant deposit separately from the expected pattern (general IHC practice). |
| Background obscures individual spermatids. | Diffuse chromogen can prevent assessment of the selective tissue pattern (HPA tissue IHC); its source cannot be assigned from appearance alone (general IHC practice). | Compare no-primary and negative-tissue controls, and review blocking, wash steps, antibody dilution, and development time (general IHC practice). |
| A listed negative tissue stains. | Adipose adipocytes or adrenal glandular cells are reported not detected (HPA tissue IHC); staining may indicate cross-reactivity or detection background (general IHC practice). | Check whether staining follows cell morphology, compare detection controls, and avoid calling it AKAP4 solely from colour intensity (general IHC practice). |
| Only a subset of seminiferous ducts appears positive. | HPA's positive call is specific to elongated or late spermatids (HPA tissue IHC); duct sections can present different germ-cell stages (general histology practice). | Identify stages in each duct before comparing scores, and record positive cells and compartment rather than averaging all ducts together (general IHC practice). |
Experiment evidence
IHC & IF images showing AKAP4 staining
A07362 · IHCImmunohistochemistry of AKAP4 in human testis tissue with AKAP4 antibody at 5 μg/ml.
A07362 · IFImmunofluorescence of AKAP4 in human testis tissue with AKAP4 antibody at 20 μg/ml.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000147081-AKAP4/tissue/cerebral+cortex#imid_5512112
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000147081-AKAP4/tissue/colon#imid_5512038
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000147081-AKAP4/tissue/liver#imid_5512047
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000147081-AKAP4/tissue/kidney#imid_5512040
HPA · ICC-IF SpermHuman Protein Atlas immunofluorescence, Sperm, antibody HPA020046; green = AKAP4, blue = nucleus, red = microtubules.
HPA · ICC-IF SpermHuman Protein Atlas immunofluorescence, Sperm, antibody HPA020046; green = AKAP4, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for AKAP4 IHC & IF
🧪Run testis first and expect staining in elongated or late spermatids (HPA: High in elongated or late spermatids); run adipose tissue as a negative, with adipocytes unstained (HPA: Not detected in adipocytes). On the testis slide, cells outside the HPA-positive spermatid population should serve as internal negative cells (HPA: High in elongated or late spermatids).
Positive control tissue: Testis (Elongated or late spermatids, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show AKAP4 in Sperm, with annotated localisation: Principal piece (enhanced) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control, an isotype control matched to the primary antibody’s host species and clonality, and AKAP4-knockout material as a biological negative (standard IHC practice). For chromogenic testis IHC, quench endogenous peroxidase and check background before scoring staining (standard IHC practice).
⚠️Feasibility: No AKAP4-specific fixation window or fixation effect is reported in the supplied evidence; the selected A07362 testis IHC caption reports 5 µg/ml but does not report a fixative (caption: A07362). Antigen-retrieval dependency is unreported, and the supplied evidence does not establish whether frozen sections or IF are easier for AKAP4. In testis, score staining by cell type and flagellar location so background is not mistaken for signal in the principal piece (HPA: High in elongated or late spermatids; HPA subcellular: principal piece).
HPA tissue IHC evidence for AKAP4
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — High 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 |
|---|---|---|---|---|
| Testis | Elongated or late spermatids | High | 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 → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced AKAP4 IHC Tips
Troubleshoot AKAP4 chromogenic IHC in paraffin sections using the selected testis image, expression data, and expected sperm flagellar localisation.
What should I change if AKAP4 staining is weak after retrieval?
Begin with citrate pH 6.0 HIER at 95–98 °C for 20 min (page IHC retrieval setting). Include testis containing spermatids as a positive control, because the selected antibody image shows testis staining and HPA reports high expression in late spermatids (A07362 caption; HPA tissue IHC). Keep section thickness, cooling, and detection conditions constant while repeating retrieval, so changes in signal can be assigned to that step (standard IHC practice). If staining remains weak, compare a second retrieval buffer or pH on adjacent sections as a fallback, recording both signal and tissue preservation (standard IHC practice).
How can I troubleshoot variable AKAP4 staining between fixed tissue samples?
The selected testis IHC caption gives an antibody concentration of 5 µg/ml but does not state the fixative (A07362 caption). AKAP4-specific fixation sensitivity is therefore unknown; neither the HPA staining pattern nor UniProt annotations establish how fixation changes this epitope (A07362 caption; HPA tissue IHC; UniProt Q5JQC9). Record fixative, fixation duration, processing schedule, and section age for each sample before comparing staining intensity (standard IHC practice). Stain similarly processed testis controls in the same run, then vary one processing condition at a time if differences persist (A07362 caption; standard IHC practice).
Which staining pattern should I expect in testis sections?
Look for staining associated with spermatids in seminiferous ducts, with attention to the developing flagellar compartment (HPA tissue IHC; UniProt Q5JQC9 localisation). HPA reports high staining in elongated or late spermatids and localises AKAP4 to the sperm principal piece (HPA tissue IHC; HPA subcellular). UniProt also describes AKAP4 as a major fibrous sheath component and annotates expression in round spermatids, so document the stage and structure being scored (UniProt Q5JQC9). Compare the signal with matched negative controls and tissue morphology before assigning diffuse nuclear or unrelated epithelial staining to AKAP4 (standard IHC practice; HPA tissue IHC).
Could precursor processing or isoforms explain inconsistent AKAP4 staining?
AKAP4 has 2 annotated isoforms and a precursor with propeptide residues 1–188 and mature chain residues 189–854 (UniProt Q5JQC9). An antibody directed to the propeptide could therefore report a different molecular population from one directed to the mature chain, if its epitope is known (UniProt Q5JQC9). Check the catalog antibody’s documented immunogen or epitope before interpreting stage dependent staining, and leave epitope specificity unresolved when that information is absent (standard IHC practice). AKAP4 also has annotated phosphorylation sites, including residues 96 and 190; their effect on this antibody’s tissue staining has not been established here (UniProt Q5JQC9).
How should I check the IHC pattern with multiplex immunofluorescence?
For a separate IF experiment, pair AKAP4 with a validated spermatid marker and inspect whether its signal follows the expected principal piece pattern (HPA tissue IHC; HPA subcellular; standard IF practice). Choose a fluorophore channel after measuring testis autofluorescence and include single stain controls when assessing overlap (standard IF practice). AKAP4 has no annotated transmembrane segment, so test permeabilisation appropriate for an intracellular epitope while following the antibody’s IF validation information, if available (UniProt Q5JQC9 topology; standard IF practice). Do not transfer the selected testis IHC image’s 5 µg/ml antibody concentration directly to IF without titration (A07362 caption; standard IF practice).
How do I reduce diffuse chromogenic background without losing spermatid signal?
Start with a no primary control to separate detection background from antibody dependent staining, and inspect staining outside seminiferous spermatids (standard IHC practice; HPA tissue IHC). For peroxidase detection, apply a peroxidase block before DAB development and use an appropriate protein block to limit nonspecific binding (standard IHC practice). Titrate the catalog antibody around the selected image concentration of 5 µg/ml, keeping retrieval and development time constant across sections (A07362 caption; standard IHC practice). If background persists, compare testis with a tissue reported as unstained, such as adipose tissue, while preserving the expected spermatid signal (HPA tissue IHC; standard IHC practice).
What is a defensible way to score AKAP4 IHC across samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the region of interest as seminiferous ducts and score the relevant spermatid compartment before examining outcome groups (HPA tissue IHC; standard IHC practice). Report the percentage of positive late spermatids and, if intensity is reproducible, an H-score using the same thresholds for every section (HPA tissue IHC; standard IHC practice). If measuring stained area or object density per mm², normalise to eligible spermatid area or count so changes in cell composition do not masquerade as expression changes (standard IHC practice). Keep exposure to DAB, counterstaining, image acquisition, and observer rules consistent, and record excluded damaged or folded regions (standard IHC practice).
When is a positive AKAP4 result likely to be artefactual?
A credible result follows spermatid and flagellar morphology, particularly the principal piece, and agrees with the selected testis image and HPA distribution (A07362 caption; HPA tissue IHC; HPA subcellular). Treat predominant staining of unrelated cells or diffuse nuclear staining cautiously because those patterns do not match the supplied AKAP4 localisation evidence (UniProt Q5JQC9 localisation; HPA tissue IHC). Signal confined to section edges, folds, or necrotic regions warrants comparison with intact tissue and a no primary control (standard IHC practice). For peroxidase and DAB detection, persistent colour in the no primary control can indicate endogenous enzyme or detection background; repeat the block and controls (standard IHC practice).
Boster reagents
Best AKAP4 / A-kinase anchor protein 4 IHC Antibodies
A07362 is listed for human IHC-P and IF (catalog: applications and reactivity), with IHC and IF images of human testis tissue (catalog: image captions).
Real IHC data
Anti-A-kinase anchor protein 4 AKAP4 Antibody
Cat # A07362
A07362 is listed for IHC-P, with an IHC image of human testis tissue at 5 μg/mL (catalog: applications; IHC image caption). A07362 is also listed for IF, with an IF image of human testis tissue at 20 μg/mL (catalog: applications; IF image caption).
Which to pick: For tissue IHC, pick A07362: IHC-P is listed, and its own IHC caption shows human testis tissue at 5 μg/mL; the caption does not report a fixative (catalog: applications; A07362 IHC image caption). For IF, pick A07362; its IF caption shows human testis tissue at 20 μg/mL, while ICC validation and clonality are unreported (catalog: IF image caption; applications; clone field). There is no cross-species choice in this catalog because A07362 lists human reactivity only (catalog: reactivity).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q5JQC9 (AKAP4_HUMAN, A-kinase anchor protein 4).
- Human Protein Atlas. AKAP4 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. AKAP4 subcellular location (ICC-IF): Localized to the principal piece..
- Human Protein Atlas. AKAP4 antibody validation summary (2 antibodies).
- The novel cancer-testis antigen A-kinase anchor protein 4 (AKAP4) is a potential target for immunotherapy of ovarian serous carcinoma. Oncoimmunology 2013 — PMC3667910.
- Evaluation of Culture Time and Media in an In Vitro Testis Organ Culture System. Birth defects research 2017 — PMC5462453.
- A novel cancer testis antigen, A-kinase anchor protein 4 (AKAP4) is a potential biomarker for breast cancer. PloS one 2013 — PMC3579772.
- Silencing of A-kinase anchor protein 4 inhibits the metastasis and growth of non-small cell lung cancer. Bioengineered 2022 — PMC8974088.
- PubMed PMID:9514854 — UniProt-cited evidence.
- PubMed PMID:9822690 — UniProt-cited evidence.
- PubMed PMID:15772651 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for AKAP4 (A-kinase anchor protein 4). Expected localisation Sperm flagellar principal piece expected (UniProt). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: A07362 at 5 μg/mL (the product's own IHC validation image is shown). Controls (HPA): positive Testis (Elongated or late spermatids); negative Adipose tissue. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Tissue sections; selected-image fixative not specified (standard IHC workflow); 2. Fixation: Image fixative and duration unreported (datasheet A07362); 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-AKAP4, 5 μg/mL (datasheet A07362); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Reported spermatid stage differs between sources (UniProt; HPA tissue IHC); Isoform / epitope: 2 isoforms; mature chain 189–854 ; epitope unknown (UniProt); Regulation: Spermatid-restricted expression (UniProt). Evidence: UniProt Q5JQC9, HPA tissue IHC · Enhanced, HPA ICC-IF · principal piece., Datasheet A07362, PMC3667910, PMC5462453. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/AKAP4/immunohistochemistry-ihc-guide.