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CLGN / Calmegin · IHC design guide
Design Immunohistochemistry for CLGN
Plan CLGN paraffin IHC around cytoplasmic staining in pachytene spermatocytes and round spermatids (HPA tissue IHC). Use testis as a positive control (HPA tissue IHC) and start the IHC-validated antibody at 2–5 μg/ml (datasheet A05261-1).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CLGN 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 | Cytoplasmic in spermatocytes and spermatids (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining in pachytene spermatocytes and round spermatids (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A05261-1) | |
| Positive control | Endometrium+1 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation conditions consistent across sections. (standard IHC practice; not target-specific) | |
| Caveat | High staining also occurs in endometrial ciliated cells (HPA tissue IHC) | |
| Regulation | Germ cell composition affects signal (HPA tissue IHC) | |
| Isoform / epitope | 2 isoforms; epitope effects are unknown (UniProt) |
Section 1
Recommended CLGN IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet A05261-1) is accompanied by published CLGN staining protocols for HCC specimens (PMC9869145; PMC12698408).
| Sample | Paraffin-embedded human mammary cancer tissue; fixative not specified (datasheet A05261-1) |
| Fixation | Image fixative and duration unreported (datasheet A05261-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet A05261-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A05261-1) |
| Primary antibody | Rabbit anti-CLGN, 2-5 μg/ml (datasheet A05261-1) |
| Primary incubation | Overnight at 4 °C (datasheet A05261-1) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A05261-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | CLGN-positive staining in ciliated epithelial cells of endometrium (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression mainly in pachytene spermatocytes and round spermatids. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval (datasheet A05261-1). For comparison, the published HCC method used citrate pH 6.0 (PMC9869145).
Section 2
What Is the Expected CLGN Staining Pattern?
CLGN is an endoplasmic reticulum membrane protein with a lumenal region at residues 20–471 and a cytoplasmic region at 493–610 (UniProt O14967 topology). In paraffin sections, expect mainly cytoplasmic staining in testicular pachytene spermatocytes and round spermatids (HPA tissue IHC profile). HPA rates the tissue staining pattern Enhanced, citing consistency with RNA expression (HPA tissue IHC reliability).
| Pachytene spermatocytes stain strongly, with staining also seen in round spermatids (HPA tissue IHC profile). | A cytoplasmic pattern in these cells fits the reported testis distribution and endoplasmic reticulum location (HPA tissue IHC profile; UniProt O14967 subcellular location). Judge the cell type and compartment together; a positive testis section is more informative than staining intensity alone (general IHC practice). |
| Signal is predominantly nuclear, or outlines the entire plasma membrane instead of appearing cytoplasmic (HPA tissue IHC profile). | This differs from the reported tissue pattern and endoplasmic reticulum membrane location (HPA tissue IHC profile; UniProt O14967 subcellular location). Treat it as suspect until a validated positive section and detection controls support it (general IHC practice). |
| Strong staining appears across cells expected to be unstained, such as adipocytes in adipose tissue (HPA tissue IHC: Not detected). | Consider antibody cross-reactivity or endogenous detection activity before assigning that signal to CLGN (general IHC practice). HPA reports high staining in pachytene spermatocytes, but no detected staining in adipose tissue adipocytes (HPA tissue IHC). |
| Color is spread through tissue or empty spaces without a clear cell-specific pattern (general IHC practice). | Diffuse background can arise from nonspecific antibody binding, incomplete blocking, or chromogen and detection background (general IHC practice). It does not reproduce HPA's mainly cytoplasmic staining in defined germ-cell populations (HPA tissue IHC profile). |
| A testis section lacks detectable staining in pachytene spermatocytes (HPA tissue IHC: High). | Treat this as an unresolved negative result: check tissue preservation, staining controls, antibody dilution, and detection performance (general IHC practice). HPA's positive testis finding sets an expectation, but it does not identify which workflow step failed (HPA tissue IHC). |
💡Expected CLGN appearanceCall the IHC result positive when mainly cytoplasmic staining is clear in pachytene spermatocytes, with round spermatids also fitting the reported profile; pachytene staining is High, while dominant nuclear or widespread cell-independent color is suspect (HPA tissue IHC; UniProt O14967 subcellular location; general IHC practice).
| Cell-type reference | HPA reports High staining in testis pachytene spermatocytes and endometrial ciliated epithelial cells; prostate and fallopian tube glandular cells have low staining (HPA tissue IHC). Interpret each tissue against its own reported cell type and level. |
| Membrane orientation and epitope | CLGN spans the membrane at residues 472–492; its lumenal and cytoplasmic regions occupy different sides (UniProt O14967 topology). An antibody's mapped epitope would help interpret access, but no epitope location or CLGN-specific retrieval effect is supplied. |
| Antibody validation | HPA048761 is IHC Supported; HPA058627 and CAB020709 are IHC Enhanced (HPA antibodies). Those ratings describe antibody-level evidence; they do not guarantee the same staining in every specimen or with every detection workflow (general IHC practice). |
| Antigen processing and isoforms | UniProt lists a signal peptide at residues 1–19, a mature chain at 20–610, and 2 isoforms (UniProt O14967). Without an antibody epitope map, these annotations cannot predict which isoform it detects or explain a missing tissue signal. |
| IF/ICC Q: What location is expected? | A: HPA supports the endoplasmic reticulum as the main ICC-IF location and additionally reports the sperm equatorial segment and mid piece (HPA subcellular). This is localisation context; the IF/ICC workflow belongs in its own guide. |
| Situation | Likely cause | Next action |
|---|---|---|
| No staining in testis pachytene spermatocytes (HPA tissue IHC: High). | Target-specific fixation effects are not established by the supplied assay evidence. Verify with a matched IHC source before attributing a result to fixation. | Check section quality and run a known-positive testis section with detection controls. Review the catalog antibody's IHC-P instructions before changing dilution or retrieval (general IHC practice). |
| Weak staining in prostate or fallopian tube glandular cells (HPA tissue IHC: Low). | Low staining is reported for these cells; weak color alone does not show assay failure (HPA tissue IHC). | Compare with the same run's testis positive control and score these cells against their reported low level (HPA tissue IHC; general IHC practice). |
| Broad, uniform color obscures the expected germ-cell pattern (HPA tissue IHC profile). | Nonspecific binding or endogenous detection activity may contribute to background (general IHC practice). | Review blocking and detection controls, then adjust antibody dilution using the IHC-validated antibody's instructions (general IHC practice). Do not score diffuse color as cell-specific CLGN. |
| Predominantly nuclear staining appears in a testis section (HPA tissue IHC profile). | The compartment conflicts with the reported cytoplasmic tissue pattern and endoplasmic reticulum location; its source remains uncertain (HPA tissue IHC; UniProt O14967 subcellular location). | Check counterstain and detection controls, then compare the same section with the expected cytoplasmic germ-cell pattern (general IHC practice; HPA tissue IHC profile). |
| Strong staining appears in adipose tissue adipocytes (HPA tissue IHC: Not detected). | Cross-reactivity or endogenous detection activity is possible; the unexpected signal alone cannot distinguish them (general IHC practice). | Check detection controls and compare with a positive testis section. Record the adipocyte result as discordant with HPA pending validation (general IHC practice; HPA tissue IHC). |
| The testis pattern varies between antibody preparations (general IHC practice). | The listed antibodies have different IHC validation ratings, and an epitope map is not supplied here (HPA antibodies). The discrepancy cannot be assigned to a particular CLGN region. | Record the antibody ID and its HPA rating, then compare cell type and compartment in matched testis sections under controlled staining conditions (HPA antibodies; general IHC practice). |
Experiment evidence
IHC & IF images showing CLGN staining
A05261-1 · IHCIHC analysis of Calmegin/CLGN using anti-Calmegin/CLGN antibody (A05261-1). Calmegin/CLGN was detected in a paraffin-embedded section of hum
A05261-1 · IHCIHC analysis of Calmegin/CLGN using anti-Calmegin/CLGN antibody (A05261-1). Calmegin/CLGN was detected in a paraffin-embedded section of hum
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000153132-CLGN/tissue/cerebral+cortex#imid_16799227
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000153132-CLGN/tissue/colon#imid_16799145
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000153132-CLGN/tissue/liver#imid_16799154
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000153132-CLGN/tissue/kidney#imid_16799147
HPA · ICC-IF PC-3Human Protein Atlas immunofluorescence, PC-3, antibody HPA048761; green = CLGN, blue = nucleus, red = microtubules.
HPA · ICC-IF PC-3Human Protein Atlas immunofluorescence, PC-3, antibody HPA048761; green = CLGN, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CLGN IHC & IF
🧪Run testis first and look for staining in pachytene spermatocytes (HPA: High in testis pachytene spermatocytes; UniProt O14967: detected in testis). Use adipose tissue as the negative tissue and assess its adipocytes (HPA: Not detected in adipose adipocytes); other cells on the testis section should show little or no specific signal relative to pachytene spermatocytes, with background judged against the negative controls (HPA: High in pachytene spermatocytes; standard IHC practice).
Positive control tissue: Endometrium (Ciliated epithelial cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CLGN in PC-3, U-251MG, U2OS, Sperm, with annotated localisation: Endoplasmic reticulum (supported) (HPA subcellular).
Technical controls: Include no-primary (secondary-only) and matched rabbit IgG isotype controls alongside a CLGN-knockout biological negative, if available (A05261-1 caption: rabbit primary antibody; standard IHC practice). Quench endogenous peroxidase before HRP/DAB detection and check the testis section for background chromogen (A05261-1 caption: HRP/DAB detection; standard IHC practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported, and the fixative is unreported in the selected A05261-1 paraffin-section caption (A05261-1 caption). That caption uses heat retrieval in EDTA at pH 8.0, but does not establish whether retrieval is required or whether other conditions work (A05261-1 caption). The supplied evidence does not establish whether frozen sections or IF are easier than paraffin IHC; in testis, distinguish pachytene spermatocytes from neighboring germ-cell stages when scoring because staining is assigned to that cell type (HPA: High in testis pachytene spermatocytes; standard IHC practice).
HPA tissue IHC evidence for CLGN
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 |
|---|---|---|---|---|
| Endometrium | Ciliated epithelial cells | High | Protein (IHC) | HPA → |
| Testis | Pachytene spermatocytes | 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 CLGN IHC Tips
Troubleshoot CLGN staining in paraffin sections by checking retrieval, staining pattern, controls and cell-specific scoring before interpreting DAB signal.
Which retrieval condition should I try first for CLGN in paraffin sections?
Start with heat-mediated retrieval in EDTA buffer at pH 8.0 (datasheet A05261-1). The selected paraffin-section image used that condition before an overnight incubation with 2 μg/ml primary antibody at 4°C (datasheet A05261-1). Keep retrieval temperature and duration consistent across comparison slides, and assess tissue preservation alongside staining intensity (standard IHC practice). If staining is weak, optimise heating duration on adjacent sections before testing another retrieval buffer as a fallback (standard IHC practice). Compare each change against a testis section containing pachytene spermatocytes, which show high CLGN staining (HPA: Testis, pachytene spermatocytes High).
Could fixation explain weak CLGN staining despite successful retrieval?
The selected paraffin-section caption does not report a fixative, so target-specific CLGN sensitivity to fixation is unknown (datasheet A05261-1). Record the fixative and fixation duration for each specimen, then compare similarly processed sections before changing antibody concentration (standard IHC practice). Check that sections remain attached and preserve cell morphology after EDTA pH 8.0 heat retrieval (datasheet A05261-1; standard IHC practice). If staining differs between specimens, repeat staining with matched processing and a positive control before assigning the difference to CLGN abundance (standard IHC practice). Do not infer fixation sensitivity from CLGN topology, phosphorylation sites or tissue staining patterns (UniProt O14967 topology and modified residues; HPA: tissue IHC).
What staining pattern fits CLGN, and when should nuclear signal raise concern?
Expect predominantly cytoplasmic staining in pachytene spermatocytes and round spermatids (HPA: tissue IHC profile). CLGN is an endoplasmic reticulum membrane protein with a lumenal region at residues 20–471 and a cytoplasmic region at 493–610 (UniProt O14967 topology). Review the DAB pattern against cell morphology and adjacent unstained structures at the same magnification (standard IHC practice). Isolated strong nuclear staining does not match the reported main endoplasmic reticulum location and warrants control review (HPA: subcellular location; standard IHC practice). Score the expected cell population separately from other cells rather than treating a whole-section colour change as equivalent evidence (HPA: tissue IHC profile; standard IHC practice).
How should epitope position and CLGN isoforms affect troubleshooting?
CLGN has 2 annotated isoforms, but the supplied evidence does not identify this antibody’s epitope or establish isoform-specific staining (UniProt O14967 isoforms; datasheet A05261-1). Map any subsequently documented immunogen to the lumenal residues 20–471, transmembrane residues 472–492 or cytoplasmic residues 493–610 before interpreting accessibility (UniProt O14967 topology; standard IHC practice). For paraffin sections, compare the documented EDTA pH 8.0 retrieval condition across matched specimens first (datasheet A05261-1; standard IHC practice). A changed staining pattern alone cannot establish isoform identity or a phosphorylation-dependent epitope (UniProt O14967 isoforms and modified residues; standard IHC practice). Seek epitope documentation or an independent specificity control before making either claim (standard IHC practice).
How can an IF follow-up clarify an ambiguous chromogenic CLGN pattern?
Use IF as a follow-up to the paraffin-section DAB result, with a marker identifying pachytene spermatocytes or round spermatids when examining testis (HPA: tissue IHC profile; standard IF practice). Choose fluorophores in channels with low tissue autofluorescence, and include unstained and single-label controls to assess bleed-through (standard IF practice). CLGN spans the endoplasmic reticulum membrane, with lumenal residues 20–471 and cytoplasmic residues 493–610 (UniProt O14967 topology). Once the antibody epitope is known, optimise permeabilisation for its membrane side while preserving the reference marker (UniProt O14967 topology; standard IF practice). Compare compartment and cell identity with the IHC result rather than equating fluorescence intensity with DAB intensity (standard IHC and IF practice).
How do I reduce diffuse DAB staining without losing CLGN-positive cells?
Inspect a no-primary control for secondary reagent, endogenous enzyme and chromogen background before changing CLGN staining conditions (standard IHC practice). Include a peroxidase block before HRP and DAB detection, especially when diffuse colour persists without primary antibody (standard IHC practice). The selected image used 10% goat serum blocking and 2 μg/ml primary antibody overnight at 4°C (datasheet A05261-1). Use those documented conditions as a starting point, then adjust blocking, washing or primary concentration one variable at a time (datasheet A05261-1; standard IHC practice). Preserve a positive control containing pachytene spermatocytes while checking whether background falls in cells reported as CLGN-negative (HPA: Testis, pachytene spermatocytes High; HPA: selected negative cells; standard IHC practice).
What should I score when comparing CLGN IHC across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population before scoring: pachytene spermatocytes and round spermatids are the reported main testis populations (HPA: tissue IHC profile). For comparable fields, report the percentage of positive target cells and an intensity-based H-score, using the same positivity threshold across sections (standard IHC practice). The conventional H-score sums each intensity category’s cell percentage multiplied by its 0–3 intensity grade, yielding 0–300 (standard IHC practice). Normalise counts to the number of evaluable target cells, or report positive-cell density per mm² of evaluable tissue when counting area (standard IHC practice). Exclude folds, section edges and necrotic regions using the same documented rules for every specimen (standard IHC practice).
How can I distinguish true CLGN staining from a convincing artefact?
Give greatest weight to cytoplasmic staining in pachytene spermatocytes and round spermatids, consistent with the reported testis pattern and endoplasmic reticulum location (HPA: tissue IHC profile; HPA: subcellular location). High staining is also reported in endometrial ciliated epithelial cells, so cell identity matters outside testis (HPA: Endometrium, ciliated epithelial cells High). Treat isolated nuclear colour, staining confined to section edges or necrotic areas, and signal reproduced without primary antibody as reasons to investigate artefact (HPA: subcellular location; standard IHC practice). Check endogenous peroxidase with a no-primary control when assessing HRP and DAB signal (standard IHC practice). The selected mammary cancer image demonstrates staining under its documented conditions but does not establish that every stained cell is CLGN-positive (datasheet A05261-1; standard IHC practice).
Boster reagents
Best CLGN / Calmegin IHC Antibodies
A05261-1 has IHC images from paraffin sections of human mammary and ovarian cancer and mouse and rat testis; no IF images are supplied (catalog image captions).
Real IHC data
Anti-Calmegin/CLGN Antibody ®
Cat # A05261-1
A05261-1 is the sole SKU with a rendered IHC card, showing a paraffin section of human mammary cancer (A05261-1 image caption). Its other IHC captions show human ovarian cancer and mouse and rat testis; the catalog lists human, mouse and rat reactivity (A05261-1 image captions; catalog applications and reactivity).
Which to pick: For tissue IHC, choose A05261-1: its own captions document paraffin sections with EDTA retrieval and 2 μg/ml primary antibody; the fixative is unreported (A05261-1 image captions). For IF/ICC, M05261 or M05261-1 are rabbit monoclonal options with IF and ICC listed, though neither has an IF image in the payload (catalog applications, clone and image fields). For cross-species IHC, A05261-1 has images from human, mouse and rat tissue; all three SKUs list reactivity with those species (A05261-1 image captions; catalog reactivity).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry O14967 (CLGN_HUMAN, Calmegin).
- Human Protein Atlas. CLGN tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. CLGN subcellular location (ICC-IF): Mainly localized to the endoplasmic reticulum. In addition localized to the equatorial segment and mid piece..
- Human Protein Atlas. CLGN antibody validation summary (3 antibodies).
- The upregulation of CLGN in hepatocellular carcinoma is potentially regulated by hsa-miR-194-3p and associated with patient progression. Frontiers in oncology 2022 — PMC9869145.
- Targeting endoplasmic reticulum stress-induced CLGN resensitizes hepatocellular carcinoma to apoptosis: paeonol synergistically enhances efficacy by dual inhibition of CLGN and NF-κB. Frontiers in oncology 2025 — PMC12698408.
- Transcriptomics, Epigenetics, and Metabolomics of Primary Aldosteronism. Cancers 2021 — PMC8583505.
- PubMed PMID:9434179 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CLGN (Calmegin). Expected localisation Cytoplasmic in spermatocytes and spermatids (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A05261-1). Validated IHC antibody: A05261-1 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Endometrium (Ciliated epithelial cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human mammary cancer tissue; fixative not specified (datasheet A05261-1); 2. Fixation: Image fixative and duration unreported (datasheet A05261-1); 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 retrieval: EDTA pH 8.0 (datasheet A05261-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A05261-1); 8. Primary antibody: Rabbit anti-CLGN, 2-5 μg/ml (datasheet A05261-1); 9. Primary incubation: Overnight at 4 °C (datasheet A05261-1). Watch for: Fixation: Keep fixation conditions consistent across sections. (standard IHC practice; not target-specific); Caveat: High staining also occurs in endometrial ciliated cells (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope effects are unknown (UniProt); Regulation: Germ cell composition affects signal (HPA tissue IHC). Evidence: UniProt O14967, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the endoplasmic reticulum. In addition localized…, Datasheet A05261-1, PMC9869145, PMC12698408. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CLGN/immunohistochemistry-ihc-guide.