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COL9A3 / Collagen alpha-3(IX) chain · IHC design guide
Design Immunohistochemistry for COL9A3
Use cartilage chondrocytes as a positive reference and adipose tissue as a negative reference for paraffin IHC (HPA tissue IHC). The catalog antibody A05963 lists an IHC dilution of 1:100–1:300 (datasheet: 1:100–1:300); expect extracellular matrix localisation (UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
COL9A3 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 | Extracellular matrix expected (UniProt) | |
| Staining pattern | High in cartilage chondrocytes; eye hyaloid membrane; compartment unclear (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Cartilage | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent (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 A05963) | |
| Caveat | Secretion may separate protein staining from source cells (HPA tissue IHC) | |
| Regulation | No expression regulator annotated (UniProt) | |
| Isoform / epitope | No isoforms; chain 26–684 is secreted; epitope unspecified (UniProt) |
Section 1
Recommended COL9A3 IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol with a published chromogenic COL9A3 tissue-staining protocol (PMC13576891).
| Sample | Paraffin-embedded human tonsil tissue; fixative not specified (datasheet A05963) |
| Fixation | Image fixative and duration unreported (datasheet A05963); 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-COL9A3, 1:100 - 1:300 (datasheet A05963) |
| 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 | COL9A3-positive staining in chondrocytes of cartilage (HPA tissue IHC: High). HPA tissue profile: Expression in hyaline cartilage and hyaloid membrane in eye. No signal in the no-primary control. |
💡Decision noteStart with the page’s citrate pH 6.0 retrieval at 95–98 °C for 20 min; use CC1 for 32 min when reproducing the published automated assay (PMC13576891).
Section 2
What Is the Expected COL9A3 Staining Pattern?
COL9A3 is a secreted, extracellular matrix collagen with no transmembrane segment (UniProt Q14050: localization and topology). In tissue IHC, expect staining associated with chondrocytes and their surrounding matrix in hyaline cartilage; HPA reports high staining in cartilage chondrocytes and expression in the eye’s hyaloid membrane (HPA tissue IHC). HPA rates its tissue IHC evidence Supported, while noting that secreted protein location may differ from RNA location (HPA tissue IHC: reliability).
| Strong staining around cartilage chondrocytes, extending into adjacent matrix. | This fits high chondrocyte staining in cartilage (HPA tissue IHC: High) and extracellular matrix localization (UniProt Q14050: localization). Record cellular and matrix staining separately, since a secreted protein may appear beyond its producing cells (HPA tissue IHC: reliability). |
| Predominantly nuclear or filament-like staining on the paraffin section, with little cartilage matrix signal. | Treat this as discordant with the expected extracellular IHC pattern (UniProt Q14050: localization; HPA tissue IHC: cartilage profile). HPA separately reports nucleoplasm and intermediate filaments in ICC-IF; that result does not establish the expected compartment in tissue IHC (HPA subcellular ICC-IF). |
| Strong staining in adipocytes or bone marrow hematopoietic cells. | These cells were not detected in the supplied HPA tissue IHC profile (HPA tissue IHC: adipose tissue and bone marrow). Check for cross-reactivity or endogenous detection activity before interpreting isolated signal as COL9A3 (general IHC practice). |
| Diffuse color across tissue and blank areas, without a recognizable cartilage pattern. | A pattern that does not follow chondrocytes or matrix is less convincing than the reported cartilage signal (HPA tissue IHC: High in chondrocytes; UniProt Q14050: extracellular matrix). Check background with an appropriate negative control (general IHC practice). |
| No signal in an intact cartilage section used as a positive control. | This conflicts with high cartilage chondrocyte staining in HPA (HPA tissue IHC: High). Verify that the section contains identifiable cartilage, then check the IHC workflow and antibody conditions; one negative run cannot establish absence of COL9A3 (general IHC practice). |
💡Expected COL9A3 appearanceCall a result positive when cartilage shows strong chondrocyte-associated staining with plausible extracellular matrix signal (HPA tissue IHC: High in chondrocytes; UniProt Q14050: localization); isolated nuclear staining or widespread color outside that pattern needs control-based review (HPA subcellular ICC-IF; general IHC practice).
| Extracellular destination and topology | COL9A3 is secreted into extracellular matrix and has no transmembrane segment (UniProt Q14050: localization and topology). Interpret matrix-associated color alongside chondrocyte-associated color rather than requiring a membrane outline. |
| Processing and molecular context | UniProt lists a signal peptide at residues 1–25 and a chain at 26–684, with no propeptide annotated (UniProt Q14050: processing). Epitope position for the IHC antibody is not supplied, so this record cannot predict how processing affects its stain. |
| Glycosylation and fixation evidence | One glycosylation site is annotated at residue 483 (UniProt Q14050: glycosylation). Neither that annotation nor the supplied HPA pattern establishes a COL9A3-specific antigen retrieval choice or fixation sensitivity. |
| Tissue evidence and antibody validation | HPA rates tissue IHC Supported and lists HPA040125 as IHC Supported (HPA tissue IHC: reliability; HPA antibodies). This supports comparison with its cartilage pattern, while HPA notes that secreted protein and RNA locations can differ and that internal RNA correlation is unavailable (HPA tissue IHC: reliability). |
| IF/ICC: Should nuclear signal define the IHC result? | No. HPA reports approved nucleoplasm and intermediate filament localization in ICC-IF images, including HeLa, Hep-G2 and U2OS (HPA subcellular ICC-IF). Its IHC tissue profile instead highlights cartilage and hyaloid membrane (HPA tissue IHC); assess paraffin sections against that tissue context and UniProt extracellular localization (UniProt Q14050). |
| Tissue choice | Cartilage provides a reported high-staining reference, whereas adipocytes and bone marrow hematopoietic cells were not detected in the supplied profile (HPA tissue IHC). A ‘not detected’ entry describes those observations, not proof that every specimen or condition must be negative. |
| Situation | Likely cause | Next action |
|---|---|---|
| Cartilage control is blank. | The result conflicts with HPA’s high cartilage chondrocyte staining (HPA tissue IHC: High); a missing target-bearing area or failed detection workflow is possible (general IHC practice). | Confirm recognizable cartilage on the section and review reagent, retrieval and detection steps against the IHC antibody’s validated instructions (general IHC practice). No COL9A3-specific retrieval condition is supplied. |
| Color covers nearly the entire section. | Uniform color obscures the expected cartilage-associated pattern (HPA tissue IHC: High in chondrocytes; UniProt Q14050: extracellular matrix); nonspecific background or endogenous detection activity is possible (general IHC practice). | Review a negative control, blocking, washes and chromogen development, then judge whether signal still follows cartilage structures (general IHC practice). |
| Adipocytes or hematopoietic cells stain strongly. | HPA reports these cell types as not detected (HPA tissue IHC: adipose tissue and bone marrow); cross-reactivity or endogenous detection activity may explain discordant color (general IHC practice). | Compare with the negative control and an identifiable cartilage positive control; describe persistent off-pattern staining as unresolved rather than assigning it to COL9A3 (general IHC practice; HPA tissue IHC: cartilage). |
| Only nuclei stain in the tissue section. | HPA’s nucleoplasmic finding comes from ICC-IF (HPA subcellular ICC-IF), while UniProt places COL9A3 extracellularly (UniProt Q14050: localization). The methods and specimens support different interpretations. | Check nuclear color against the negative control and assess whether cartilage has the reported chondrocyte-associated pattern before scoring tissue IHC as positive (general IHC practice; HPA tissue IHC: cartilage). |
| Matrix color is present but chondrocyte outlines are weak. | An extracellular signal can lie beyond producing cells (UniProt Q14050: localization; HPA tissue IHC: reliability), so weak cell outlines alone do not establish failure. | Score matrix and cell-associated staining separately, confirm tissue identity and compare the distribution with the cartilage positive control (general IHC practice; HPA tissue IHC: High in chondrocytes). |
| A negative-reference tissue shows a small focal signal. | HPA ‘not detected’ is an observed tissue profile, not a universal exclusion rule (HPA tissue IHC: negative entries). Focal color may need review for background or tissue-specific context (general IHC practice). | Check the cell type and section morphology, compare negative-control color, and report a reproducible discordance without changing the expected cartilage call (general IHC practice; HPA tissue IHC: cartilage profile). |
Experiment evidence
IHC & IF images showing COL9A3 staining
A05963 · IHCImmunohistochemistry analysis of paraffin-embedded human tonsil tissue, using Collagen IX alpha3 Antibody. The picture on the right is block
A05963 · IFImmunofluorescence analysis of NIH/3T3 cells, using Collagen IX alpha3 Antibody. The picture on the right is blocked with the synthesized pe
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000092758-COL9A3/tissue/cerebral+cortex#imid_20285417
HPA · EyeHuman Protein Atlas IHC, Eye. Source: https://www.proteinatlas.org/ENSG00000092758-COL9A3/tissue/retina#imid_977
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000092758-COL9A3/tissue/colon#imid_20285327
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000092758-COL9A3/tissue/liver#imid_20285336
HPA · ICC-IF HeLaHuman Protein Atlas immunofluorescence, HeLa, antibody HPA058323; green = COL9A3, blue = nucleus, red = microtubules.
HPA · ICC-IF HeLaHuman Protein Atlas immunofluorescence, HeLa, antibody HPA058323; green = COL9A3, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for COL9A3 IHC & IF
🧪Run cartilage first and require staining in chondrocytes (HPA: High in cartilage chondrocytes); use adipose tissue as the negative comparator (HPA: Not detected in adipocytes). On the cartilage slide, use any non-chondrocyte cells present as a provisional internal negative for cell-associated staining, while recognizing that extracellular matrix signal may be genuine (HPA: High in chondrocytes; UniProt Q14050: extracellular matrix).
Positive control tissue: Cartilage (Chondrocytes, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show COL9A3 in HeLa, Hep-G2, U2OS, with annotated localisation: Nucleoplasm (approved) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and an isotype control matched to the primary antibody’s host species, immunoglobulin class, and clonality (standard IHC practice). Include a peptide-block control, as shown for the catalog antibody in paraffin-embedded tonsil tissue (A05963 caption); quench endogenous peroxidase for chromogenic IHC, block endogenous biotin if using biotin detection, and check cartilage autofluorescence if using IF (standard IHC/IF practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected paraffin-section caption does not state a fixative (A05963 caption). Retrieval dependence is unreported; optimize antigen retrieval for paraffin cartilage sections with the controls above (standard IHC practice). The supplied evidence does not establish that frozen sections or IF are easier; assess cartilage matrix autofluorescence for IF, and validate localization separately because HPA ICC-IF reports nucleoplasm and intermediate filaments whereas UniProt places COL9A3 in extracellular matrix (HPA: subcellular; UniProt Q14050: extracellular matrix).
HPA tissue IHC evidence for COL9A3
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — At least one protein variant secreted, tissue location of RNA and protein might differ and correlation is complex. External characterization data supports antibody staining but no internal RNA data available for correlation.). 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 |
|---|---|---|---|---|
| Cartilage | Chondrocytes | 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 COL9A3 IHC Tips
Troubleshoot COL9A3 staining by evaluating extracellular matrix signal, assay controls, and the limits of the available tissue evidence.
Which retrieval conditions should I start with for COL9A3 paraffin sections?
Start with citrate buffer at pH 6.0, heated to 95–98 °C for 20 minutes (page retrieval setting). Allow slides to cool in buffer, then compare staining with a matched section processed without retrieval (standard IHC practice). The selected catalog antibody has a paraffin-section tonsil image with peptide-blocked staining, but its caption does not report retrieval conditions or fixative (A05963 image caption). Assess whether retrieval reveals matrix-associated signal rather than diffuse nuclear color, because COL9A3 is annotated as a secreted extracellular-matrix chain (UniProt Q14050 localization). Keep section thickness, detection chemistry, and exposure to chromogen consistent while optimizing retrieval (standard IHC practice).
How should I troubleshoot weak COL9A3 staining when fixation history varies?
Target-specific sensitivity to fixation is unknown from the supplied evidence; record each specimen’s fixative and fixation duration before comparing staining (A05963 image caption; standard IHC practice). The selected paraffin-section caption does not state a fixative, so it cannot establish an optimal fixation condition (A05963 image caption). Compare matched sections through the same citrate pH 6.0, 95–98 °C, 20-minute retrieval and identical detection steps (page retrieval setting; standard IHC practice). Include a known positive cartilage section when available, since high staining is reported in cartilage chondrocytes (HPA tissue IHC). If archival samples differ, report fixation history alongside results instead of attributing a difference to fixation alone (standard IHC practice).
What staining pattern is biologically plausible for COL9A3 in tissue sections?
Prioritize matrix-associated staining around relevant cartilage structures: COL9A3 is a secreted extracellular-matrix component of hyaline cartilage and vitreous (UniProt Q14050 localization and function). HPA reports high staining in cartilage chondrocytes and describes expression in hyaline cartilage and the eye’s hyaloid membrane (HPA tissue IHC). Its ICC/IF subcellular page instead reports nucleoplasmic and intermediate-filament localization in imaged cell lines, a discordance to document rather than silently transfer to tissue IHC (HPA subcellular). Inspect a hematoxylin counterstain and compare adjacent matrix and cells before assigning the signal to a compartment (standard IHC practice). Nuclear-only chromogenic staining needs independent corroboration before interpretation as the expected tissue pattern (UniProt Q14050 localization; standard IHC practice).
How do processing and epitope location affect COL9A3 staining?
The annotated COL9A3 precursor has 684 amino acids, a signal peptide at residues 1–25, and a mature chain spanning 26–684 (UniProt Q14050 processing). No isoforms or domains are annotated, while one glycosylation site is listed at residue 483 (UniProt Q14050 record). Check the catalog antibody’s documented immunogen or epitope before deciding whether processing could remove its binding site (standard IHC practice). The peptide-blocked tonsil image supports competition of staining by the supplied peptide, but does not identify the epitope’s location or establish tissue specificity on its own (A05963 image caption; standard IHC practice). Compare serial sections and controls under identical retrieval before attributing variable signal to epitope accessibility (standard IHC practice).
How should I adapt COL9A3 evaluation to multiplex IF?
For the separate IF/ICC workflow, pair COL9A3 with a marker that identifies chondrocytes when imaging cartilage, since HPA reports high cartilage chondrocyte staining (HPA tissue IHC). Choose fluorophores after inspecting unstained tissue in each channel, and favor a channel with lower tissue autofluorescence for a weak COL9A3 signal (standard IF practice). COL9A3 has a signal peptide and no transmembrane segment, so extracellular matrix is the expected accessible compartment for the mature chain (UniProt Q14050 processing and topology). Begin without detergent permeabilisation for an extracellular epitope; test a mild permeabilised condition only if the antibody’s documented epitope or intracellular staining objective warrants it (standard IF practice). Assess channel bleed-through and localization with single-stain controls (standard IF practice).
How can I reduce diffuse chromogenic background without losing matrix signal?
Compare no-primary and isotype-appropriate controls with the test section to identify detection-system background (standard IHC practice). Block endogenous peroxidase before an HRP/DAB readout, then titrate primary antibody and chromogen development using the same retrieval condition across sections (standard IHC practice; page retrieval setting). Matrix-associated staining deserves careful review because COL9A3 is secreted into extracellular matrix (UniProt Q14050 localization). The selected tonsil image includes peptide-blocked staining, but that control alone does not exclude background from tissue edges or endogenous enzyme activity (A05963 image caption; standard IHC practice). Check whether diffuse color remains in the no-primary section before changing antigen retrieval (standard IHC practice).
What should I measure when COL9A3 staining is predominantly extracellular? ⚠ ANSWER MARKED FOR VERIFICATION
Define cartilage regions on the counterstained section before scoring, and exclude folds, torn edges, and necrotic areas (standard IHC practice). Measure positive matrix area or optical density per mm² of evaluable matrix, keeping stain threshold and chromogen development constant across specimens (standard IHC practice). Report the stained fraction alongside tissue area and, if useful, chondrocyte density per mm² so differences in matrix abundance are visible (standard IHC practice). A cell-based H-score or percent-positive-cell score may miss deposited extracellular COL9A3, which is annotated as secreted matrix protein (UniProt Q14050 localization; standard IHC practice). Compare batches using the same positive control section and scoring rules (standard IHC practice).
When should I question an apparent COL9A3-positive tissue result?
Look for reproducible matrix-associated signal in an appropriate region: COL9A3 is a secreted extracellular-matrix chain, and HPA reports high cartilage chondrocyte staining (UniProt Q14050 localization; HPA tissue IHC). Treat nuclear-only color or staining restricted to a tissue edge as questionable until serial sections and controls support it (UniProt Q14050 localization; standard IHC practice). Exclude necrotic regions and compare a no-primary section to assess nonspecific deposition or endogenous peroxidase in an HRP/DAB assay (standard IHC practice). The tonsil paraffin image demonstrates peptide-blockable staining for SKU A05963, without reporting its fixative or establishing the cause of every positive signal (A05963 image caption). Interpret negative staining against an included positive control before concluding that COL9A3 is absent (standard IHC practice).
Boster reagents
Best COL9A3 / Collagen alpha-3(IX) chain IHC Antibodies
A05963 has IHC data from paraffin-embedded human tonsil and IF data from NIH/3T3 cells (catalog image captions); listed reactivity covers human, mouse, and rat (catalog reactivity).
Real IHC data
Anti-Collagen IX alpha3 COL9A3 Antibody
Cat # A05963
A05963 will render with its IHC figure from paraffin-embedded human tonsil, including a synthesized-peptide-blocked comparison (A05963 IHC caption). It is listed for IHC, IF, ICC, and ELISA, with a separate IF image from NIH/3T3 cells (catalog applications; A05963 IF caption).
Which to pick: Choose A05963 for paraffin-section tissue IHC because its own figure shows human tonsil; the fixative is unreported (A05963 IHC caption). For IF/ICC, A05963 is listed for both applications, and its IF image shows NIH/3T3 cells (catalog applications; A05963 IF caption). For cross-species work, A05963 is a rabbit polyclonal antibody with stated human, mouse, and rat reactivity (catalog host, dilution_raw, reactivity).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q14050 (CO9A3_HUMAN, Collagen alpha-3(IX) chain).
- Human Protein Atlas. COL9A3 tissue IHC expression (reliability: Supported).
- Human Protein Atlas. COL9A3 subcellular location (ICC-IF): Mainly localized to the nucleoplasm. In addition localized to the intermediate filaments..
- Human Protein Atlas. COL9A3 antibody validation summary (2 antibodies).
- Functional validation of driver mutation-specific uveal melanoma biomarkers: role of COL9A3 in cancer cell plasticity. The Journal of pathology 2026 — PMC13576891.
- Transcriptomic alterations underlying metaplasia into specific metaplastic components in metaplastic breast carcinoma. Breast cancer research : BCR 2023 — PMC9883935.
- USP3 promotes gastric cancer progression and metastasis by deubiquitination-dependent COL9A3/COL6A5 stabilisation. Cell death & disease 2021 — PMC8688524.
- PubMed PMID:8586434 — UniProt-cited evidence.
- PubMed PMID:10428822 — UniProt-cited evidence.
- PubMed PMID:11780052 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for COL9A3 (Collagen alpha-3(IX) chain). Expected localisation Extracellular matrix expected (UniProt). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: A05963 at 1:100 - 1:300 (the product's own IHC validation image is shown). Controls (HPA): positive Cartilage (Chondrocytes); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human tonsil tissue; fixative not specified (datasheet A05963); 2. Fixation: Image fixative and duration unreported (datasheet A05963); 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-COL9A3, 1:100 - 1:300 (datasheet A05963); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent (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 A05963); Caveat: Secretion may separate protein staining from source cells (HPA tissue IHC); Isoform / epitope: No isoforms; chain 26–684 is secreted; epitope unspecified (UniProt); Regulation: No expression regulator annotated (UniProt). Evidence: UniProt Q14050, HPA tissue IHC · Supported, HPA ICC-IF · Mainly localized to the nucleoplasm. In addition localized to the…, Datasheet A05963, PMC13576891. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/COL9A3/immunohistochemistry-ihc-guide.