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C1QBP / Complement component 1 Q subcomponent-binding protein, mitochondrial · IHC design guide
Design Immunohistochemistry for C1QBP
Plan chromogenic C1QBP IHC around granular cytoplasmic tissue staining (HPA tissue IHC). This guide covers fixation, controls and scoring while accounting for reported secretion (UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
C1QBP 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 | Granular cytoplasm in tissue (HPA tissue IHC) | |
| Staining pattern | Cells broadly show granular cytoplasmic staining (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet M01439) | |
| Positive control | Appendix+4 more · see all | |
| Negative control | Liver+1 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 | Secretion may complicate cell-associated staining (UniProt) | |
| Regulation | Activated lymphocytes secrete C1QBP (UniProt) | |
| Isoform / epitope | No annotated isoforms; mature chain spans residues 74–282 (UniProt) |
Section 1
Recommended C1QBP IHC & IF Protocols
The catalog antibody’s IHC protocol uses EDTA pH 8.0 retrieval (datasheet M01439). One published paraffin section protocol is included below (PMC13069790).
| Sample | Paraffin-embedded human breast cancer tissue; fixative not specified (datasheet M01439) |
| Fixation | Image fixative and duration unreported (datasheet M01439); 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 M01439); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet M01439) |
| Primary antibody | Rabbit monoclonal (clone 17C69) anti-C1QBP, 1:50-1:200 (datasheet M01439) |
| Primary incubation | Overnight at 4 °C (datasheet M01439) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet M01439) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | C1QBP-positive staining in germinal center cells of appendix (HPA tissue IHC: High). HPA tissue profile: Ubiquitous cytoplasmic expression with a granular pattern. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval (datasheet M01439); the published mouse lung protocol reports retrieval without specifying its buffer or conditions (PMC13069790).
Section 2
What Is the Expected C1QBP Staining Pattern?
C1QBP is predominantly mitochondrial (UniProt Q07021), while tissue IHC shows ubiquitous, granular cytoplasmic staining (HPA: Supported; HPA: low tissue specificity). Strong staining is reported in germinal center cells, glandular cells, endocrine cells, ovarian follicle cells and splenic white pulp cells (HPA: High in each listed cell type). Cell surface expression is also reported (UniProt Q07021); C1QBP has no transmembrane segment (UniProt Q07021 topology).
| Granular cytoplasmic staining in the expected cells, with stronger signal in germinal centers or endocrine cells. | This fits the tissue IHC profile (HPA: ubiquitous granular cytoplasm; High in germinal center and endocrine cells). Compare cells within the same section; the profile does not require equal intensity everywhere (HPA: low tissue specificity; variable reported staining levels). |
| Predominantly nuclear, nucleolar or smooth diffuse staining, with little granular cytoplasm. | This departs from the usual tissue IHC pattern (HPA: granular cytoplasm). Nuclear and nucleolar localization are reported (UniProt Q07021), so compartment alone cannot prove artefact. Check whether the pattern is restricted to identifiable cells and survives appropriate controls (general IHC practice). |
| Strong staining in cholangiocytes or skeletal myocytes while nearby expected cells stain weakly. | Those cell types were not detected in the supplied tissue profile (HPA: cholangiocytes and skeletal myocytes, Not detected). Cross-reactivity or endogenous chromogen activity is possible; compare a control without primary antibody and an expected positive section (general IHC practice). |
| A broad haze or uniform color over cells, stroma and blank areas. | That distribution does not resemble the reported cellular granules (HPA: granular cytoplasm). Background from nonspecific binding, endogenous detection activity or incomplete washing can obscure interpretation; inspect the control without primary antibody (general IHC practice). |
| No staining in an expected positive section, including its germinal center or endocrine cells. | This conflicts with the supplied positive profile (HPA: High in germinal center and endocrine cells). First verify that the expected cells are present, then check the antibody, detection reagents and run controls (general IHC practice); a blank slide alone cannot establish absent C1QBP. |
💡Expected C1QBP appearanceCall a positive IHC result when identifiable germinal center, glandular, endocrine, follicle or white pulp cells show granular cytoplasmic staining, potentially strong in these reported high groups (HPA: High; HPA: granular cytoplasm); broad acellular haze or isolated staining of HPA-undetected cell types warrants control review (HPA: cholangiocytes and skeletal myocytes, Not detected; general IHC practice).
| Cell population and tissue choice | The RNA profile has low tissue specificity, but reported protein intensity differs by cell type (HPA: low tissue specificity; High, Low and Not detected groups). Score the named cell population rather than treating a whole section as uniformly positive (general IHC practice). |
| Compartment and assay | Tissue IHC is described as granular cytoplasmic (HPA: tissue IHC). ICC-IF instead lists plasma membrane as the main location and mitochondria as an additional location (HPA: ICC-IF, both supported). Interpret each assay against its own evidence. |
| Processing and cell surface signal | The annotated mature chain spans residues 74–282 and no transmembrane segment is annotated (UniProt Q07021 processing and topology). Cell surface expression is reported for macrophages and monocyte-derived dendritic cells (UniProt Q07021). The supplied record gives no antibody epitope, so it cannot predict which forms this antibody detects. |
| Extracellular distribution | A secreted form is reported, including secretion by activated lymphocytes (UniProt Q07021). HPA notes that secreted variants can complicate RNA–protein correspondence (HPA: reliability description). Extracellular color alone therefore does not identify its producing cell; assess cellular morphology and controls (general IHC practice). |
| Validation and retrieval limits | The tissue pattern has Supported reliability (HPA: tissue IHC), and HPA026483 is listed as IHC Supported (HPA: antibody validation). Neither entry supplies an antigen retrieval condition or target-specific fixation effect; use the IHC-validated antibody’s documented conditions if available (general IHC practice). |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected positive tissue is blank. | The section may lack the reported positive cells (HPA: cell-specific High groups), or an IHC reagent or run step may have failed (general IHC practice). | Confirm cell identity on the section and inspect a concurrently processed positive control; review antibody dilution, detection and chromogen steps against the antibody instructions (general IHC practice). |
| Only uniformly dark tissue or diffuse haze is visible. | The pattern differs from granular cytoplasm (HPA: tissue IHC). Nonspecific binding or endogenous detection activity can contribute (general IHC practice). | Compare the control without primary antibody; review blocking, washing and chromogen development, then score only discrete cellular signal (general IHC practice). |
| Cholangiocytes or skeletal myocytes appear strongly positive. | These cells are reported as Not detected (HPA: tissue IHC); cross-reactivity or endogenous detection activity is possible (general IHC practice). | Check a control without primary antibody and an expected positive cell population in the same run; withhold a C1QBP call if control staining persists (general IHC practice). |
| Signal appears nuclear or nucleolar with little cytoplasmic granularity. | This is atypical for the tissue IHC profile (HPA: granular cytoplasm), although nuclear and nucleolar localization is reported (UniProt Q07021). | Record the cell type and distribution, compare with a positive tissue and the control without primary antibody, and avoid calling artefact from location alone (general IHC practice). |
| Some cells in an otherwise positive section look weak or negative. | Reported levels vary across cell populations, from High to Low or Not detected (HPA: tissue IHC); whole-section uniformity is not expected from those observations. | Score identified cell populations separately and compare their staining with the supplied HPA cell-type profile (HPA: tissue IHC; general IHC practice). |
| IF/ICC shows a membrane pattern: does that contradict the IHC result? | HPA assigns plasma membrane as the main ICC-IF location and mitochondria as an additional one (HPA: ICC-IF, both supported); its tissue IHC summary describes granular cytoplasm (HPA: tissue IHC). | Use the assay-specific pattern to interpret each result; for IF/ICC design and controls, consult its separate guide (HPA: ICC-IF; general IHC/IF practice). |
Experiment evidence
IHC & IF images showing C1QBP staining
M01439 · IHCIHC analysis of C1QBP using anti-C1QBP antibody (M01439). C1QBP was detected in a paraffin-embedded section of human breast cancer tissue. H
M01439 · IHCIHC analysis of C1QBP using anti-C1QBP antibody (M01439). C1QBP was detected in a paraffin-embedded section of human pancreas cancer tissue.
PB9921 · IHCIHC analysis of C1QBP using anti-C1QBP antibody (PB9921). C1QBP was detected in paraffin-embedded section of human tonsil tissues. Heat medi
PB9921 · IHCIHC analysis of C1QBP using anti-C1QBP antibody (PB9921). C1QBP was detected in paraffin-embedded section of mouse spleen tissues. Heat medi
PB9921 · IFIF analysis of C1QBP using anti-C1QBP antibody (PB9921). C1QBP was detected in immunocytochemical section of U20S cell. Enzyme antigen retri
M01439-1 · IHCIHC analysis of C1QBP using anti-C1QBP antibody (M01439-1). C1QBP was detected in a paraffin-embedded section of human breast cancer tissue.
M01439-1 · IHCIHC analysis of C1QBP using anti-C1QBP antibody (M01439-1). C1QBP was detected in a paraffin-embedded section of human pancreas cancer tissu
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000108561-C1QBP/tissue/cerebral+cortex#imid_6468056
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000108561-C1QBP/tissue/colon#imid_6467974
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000108561-C1QBP/tissue/liver#imid_6467983
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000108561-C1QBP/tissue/kidney#imid_6467984
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA026483; green = C1QBP, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA026483; green = C1QBP, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for C1QBP IHC & IF
🧪Run breast first: glandular cells should stain (HPA: breast glandular cells High). Use liver cholangiocytes as a negative tissue comparator (HPA: liver cholangiocytes Not detected); on the breast slide, neighboring cells without specific chromogen deposition can serve as internal negative comparators, without assigning an unverified negative cell type.
Positive control tissue: Appendix (Germinal center cells, HPA High)
Negative control tissue: Liver (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show C1QBP in A-431, U-251MG, U2OS, KOLF2.1J, with annotated localisation: Plasma membrane (supported) (HPA subcellular).
Technical controls: Include no-primary (secondary-only) and matched rabbit IgG isotype controls for the rabbit primary (M01439 tissue-IHC caption: rabbit antibody), plus C1QBP knockout material as a biological specificity control if available. Block endogenous peroxidase and check for background chromogen deposition in the breast section before scoring (M01439 tissue-IHC caption: peroxidase detection with DAB).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported in the supplied evidence, and the selected M01439 tissue-IHC caption does not state the fixative. The caption uses heat retrieval in EDTA at pH 8.0, but does not establish that retrieval is required (M01439 tissue-IHC caption). The supplied evidence does not establish whether frozen sections or IF would be easier; for breast sections, endogenous peroxidase can complicate DAB interpretation (M01439 tissue-IHC caption: breast tissue and peroxidase/DAB detection).
HPA tissue IHC evidence for C1QBP
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — High consistency between antibody staining and RNA expression data. At least one protein variant secreted, tissue location of RNA and protein might differ and correlation is complex.). 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 |
|---|---|---|---|---|
| Appendix | Germinal center cells | High | Protein (IHC) | HPA → |
| Breast | Glandular cells | High | Protein (IHC) | HPA → |
| Colon | Endocrine cells | High | Protein (IHC) | HPA → |
| Lymph node | Germinal center cells | High | Protein (IHC) | HPA → |
| Ovary | Follicle cells | High | Protein (IHC) | HPA → |
Section 3
Advanced C1QBP IHC Tips
Troubleshoot C1QBP staining in paraffin sections by checking retrieval, compartment patterns, controls and scoring before interpreting chromogenic signal.
What retrieval should I try first when C1QBP staining is weak?
Start with heat-mediated retrieval in EDTA at pH 8.0 (datasheet M01439). This condition accompanies C1QBP staining in a paraffin section of human breast cancer tissue with the catalog antibody at 1:50, incubated overnight at 4°C (datasheet M01439). If signal is weak, first check that heating and cooling were consistent across sections, then compare a modestly longer retrieval time on matched sections (standard IHC practice). Use a known positive control, such as breast glandular cells, when judging improvement (HPA: High in breast glandular cells). Excess retrieval can damage morphology, so assess staining and tissue preservation together (standard IHC practice).
How should I troubleshoot weak staining when fixation history is uncertain?
The selected tissue caption identifies a paraffin section but does not state its fixative, so target-specific fixation sensitivity is unknown (datasheet M01439: fixative not stated). Record the fixative and fixation duration for each specimen, and compare sections processed under the same conditions (standard IHC practice). Begin with the documented EDTA retrieval at pH 8.0 before changing other variables (datasheet M01439). If a previously reliable control also weakens, check section age, retrieval performance and detection reagents (standard IHC practice). Do not infer a fixation effect from C1QBP localisation or modified residues; neither establishes fixation sensitivity (UniProt Q07021 topology and modified residues).
Which staining compartments are plausible for C1QBP in paraffin sections?
Expect a granular cytoplasmic pattern in tissue IHC (HPA: ubiquitous granular cytoplasmic expression). Mitochondrial localisation is predominant in the protein record, while nuclear, nucleolar, membrane, secreted and cytoplasmic locations are also listed (UniProt Q07021 subcellular location). A membrane accent may be biologically plausible, although membrane staining alone merits validation against controls and cell context (HPA subcellular: plasma membrane supported; standard IHC practice). For a compartment question, compare the chromogenic pattern with a marker on adjacent sections and score compartments separately (standard IHC practice). Document whether retrieval at pH 8.0 changes distribution as well as intensity (datasheet M01439; standard IHC practice).
Could epitope location explain discordant C1QBP staining patterns?
The record lists 0 annotated isoforms and a mature chain spanning residues 74–282, but the catalog antibody's epitope is not supplied (UniProt Q07021 isoforms and processing; datasheet M01439). C1QBP has no annotated transmembrane segment, so membrane staining does not identify an epitope orientation by itself (UniProt Q07021 topology). Reported modified residues include serine 87 and tyrosine 188; their presence does not establish antibody sensitivity to modification (UniProt Q07021 modified residues). If compartments disagree between specimens, compare retrieval and detection under matched conditions before assigning a molecular explanation (standard IHC practice). Request epitope information or use an independently validated antibody to investigate that explanation (standard IHC practice).
How can IF help assess an ambiguous C1QBP IHC pattern?
Use IF/ICC as a separate exploratory assay when a chromogenic compartment call needs checking; the supplied catalog evidence documents paraffin-section IHC, not an IF protocol (datasheet M01439). Multiplex C1QBP with a marker for the expected cell type, chosen from the tissue question, and include single-channel controls (standard IF practice). Select fluorophores after checking tissue autofluorescence, favoring a spectral window with lower background for the weaker signal (standard IF practice). For intracellular C1QBP, permeabilise sufficiently to reach the mitochondrial or nuclear epitope; for a proposed surface signal, compare a nonpermeabilised preparation (UniProt Q07021 subcellular location; standard IF practice). Do not transfer the IHC antibody dilution of 1:50 directly to IF (datasheet M01439; standard IF practice).
What should I check when C1QBP DAB staining looks diffuse?
Compare the stained section with a primary-omission control to identify signal from the detection system (standard IHC practice). The documented workflow used 10% goat serum blocking, a 1:50 primary incubation overnight at 4°C, and DAB development (datasheet M01439). If diffuse signal persists, review the peroxidase block, washing and DAB development time on matched sections (standard IHC practice). Do not score pigment, folds or tissue edges as C1QBP merely because they are brown (standard IHC practice). A convincing pattern should resolve into cells and compartments, with granular cytoplasmic staining providing a tissue-IHC reference (HPA: ubiquitous granular cytoplasmic expression).
How should I score C1QBP staining across tissue samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, because tissue IHC commonly shows granular cytoplasmic C1QBP (HPA: ubiquitous granular cytoplasmic expression). For cell staining, record the percentage of positive cells and intensity to calculate an H-score on the conventional 0–300 scale (standard IHC practice). If spatial distribution matters, report positive-cell density per mm² of viable tissue and state the analysed area (standard IHC practice). Normalise comparisons to the same cell type, compartment, section quality and staining batch (standard IHC practice). Keep glandular cells, immune cells and stromal cells separate when their proportions differ between samples (HPA tissue IHC: cell-type-specific expression; standard IHC practice).
How do I distinguish genuine C1QBP staining from artefact?
Look first for cell-associated granular cytoplasmic staining, the tissue-IHC pattern reported for C1QBP (HPA: ubiquitous granular cytoplasmic expression). Check whether strongly stained cells fit a supported tissue context, such as breast glandular cells or lymph-node germinal center cells (HPA: High in breast glandular cells and lymph-node germinal center cells). Treat isolated nuclear staining cautiously while recognising that nuclear and nucleolar locations are recorded for C1QBP (UniProt Q07021 subcellular location). Exclude section edges, necrotic regions and endogenous peroxidase signal with morphology and a primary-omission control (standard IHC practice). Interpret membrane signal in cellular context because surface expression is reported for macrophages and monocyte-derived dendritic cells (UniProt Q07021 tissue specificity).
Boster reagents
Best C1QBP / Complement component 1 Q subcomponent-binding protein, mitochondrial IHC Antibodies
Anti-C1QBP antibodies have IHC images from human breast cancer and tonsil sections, plus mouse and rat tissues; one also has an IF image from U20S cells (catalog image captions).
Real IHC data
Anti-GC1q R Rabbit Monoclonal Antibody
Cat # M01439
Real IHC data
Anti-GC1q R/C1QBP Antibody ®
Cat # PB9921
Real IHC data
Anti-C1QBP Rabbit Monoclonal Antibody
Cat # M01439-1
M01439 has paraffin-section IHC images from human breast and pancreas cancers and mouse and rat midbrain; M01439-1 has images from human breast and pancreas cancers and rat cerebellum (catalog IHC captions). PB9921 has paraffin-section IHC images from human tonsil and mouse and rat spleen, plus an IF image from U20S cells (catalog image captions).
Which to pick: For paraffin-section IHC, choose rabbit monoclonal M01439 or M01439-1 when their imaged tissues match your study; each caption uses EDTA retrieval at pH 8.0 and a 1:50 primary dilution (catalog product details and IHC captions). For IF/ICC, choose PB9921: IF and ICC are listed applications, and its U20S cell IF caption uses 2 μg/mL primary antibody (catalog applications and IF caption). All three list human, mouse and rat reactivity, but their IHC captions document different tissues and retrieval conditions; the fixative is unreported in those captions (catalog reactivity and IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q07021 (C1QBP_HUMAN, Complement component 1 Q subcomponent-binding protein, mitochondrial).
- Human Protein Atlas. C1QBP tissue IHC expression (reliability: Supported).
- Human Protein Atlas. C1QBP subcellular location (ICC-IF): Mainly localized to the plasma membrane. In addition localized to the mitochondria..
- Human Protein Atlas. C1QBP antibody validation summary (1 antibodies).
- Complement C1q binding protein regulates T cells' mitochondrial fitness to affect their survival, proliferation, and anti-tumor immune function. Cancer science 2022 — PMC8898709.
- Complement component 1q subcomponent binding protein in the brain of the rat. Scientific reports 2019 — PMC6418184.
- C1QBP Associated With Immune Infiltration Predicts Poor Prognosis in Lung Adenocarcinoma. Cancer informatics 2026 — PMC12901909.
- Complement protein C1q induces endothelial apoptosis through C1qBP regulation of mitochondrial function in lung endothelial cells in systemic sclerosis. Molecular medicine (Cambridge, Mass.) 2026 — PMC13069790.
- PubMed PMID:8262387 — UniProt-cited evidence.
- PubMed PMID:8195709 — UniProt-cited evidence.
- PubMed PMID:11278463 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for C1QBP (Complement component 1 Q subcomponent-binding protein, mitochondrial). Expected localisation Granular cytoplasm in tissue (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet M01439). Validated IHC antibody: M01439 at 1:50-1:200 (the product's own IHC validation image is shown). Controls (HPA): positive Appendix (Germinal center cells); negative Liver. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human breast cancer tissue; fixative not specified (datasheet M01439); 2. Fixation: Image fixative and duration unreported (datasheet M01439); 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 M01439); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet M01439); 8. Primary antibody: Rabbit monoclonal (clone 17C69) anti-C1QBP, 1:50-1:200 (datasheet M01439); 9. Primary incubation: Overnight at 4 °C (datasheet M01439). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Secretion may complicate cell-associated staining (UniProt); Isoform / epitope: No annotated isoforms; mature chain spans residues 74–282 (UniProt); Regulation: Activated lymphocytes secrete C1QBP (UniProt). Evidence: UniProt Q07021, HPA tissue IHC · Supported, HPA ICC-IF · Mainly localized to the plasma membrane. In addition localized to…, Datasheet M01439, PMC13069790. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/C1QBP/immunohistochemistry-ihc-guide.