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- Table of Contents
Plan CCAR2 staining in paraffin sections using the ubiquitous nuclear tissue pattern as a reference (HPA tissue IHC). This guide covers fixation consistency, controls, chromogenic detection, and scoring.
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
| Expected localisation | Nuclear staining across tissues (HPA tissue IHC) | |
| Staining pattern | Widespread nuclear staining across cell types (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A03412-1) | |
| Positive control | Bronchus+4 more · see all | |
| Negative control | Lung |
| Fixation | Keep fixation consistent across sections (standard IHC practice; not target-specific) | |
| Caveat | UV-induced apoptosis may shift CCAR2 to cytoplasm (UniProt) | |
| Regulation | Rises with gastric carcinoma progression (UniProt) | |
| Isoform / epitope | 2 isoforms; check antibody epitope coverage (UniProt) |
The catalog antibody’s IHC-P protocol is followed by three published CCAR2 staining protocols (datasheet A03412-1; PMC13229996; PMC4335761; PMC5787426).
| Sample | Paraffin-embedded human gall bladder adenosquamous carcinoma tissue; fixative not specified (datasheet A03412-1) |
| Fixation | Image fixative and duration unreported (datasheet A03412-1); 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 A03412-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A03412-1) |
| Primary antibody | Rabbit anti-CCAR2, 1-2 μg/ml (datasheet A03412-1) |
| Primary incubation | Overnight at 4 °C (datasheet A03412-1) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A03412-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | CCAR2-positive staining in respiratory epithelial cells of bronchus (HPA tissue IHC: High). HPA tissue profile: Ubiquitous nuclear expression. No signal in the no-primary control. |
CCAR2 should appear predominantly in nuclei across many cell types (HPA tissue IHC: ubiquitous nuclear expression; UniProt Q8N163: nucleus). Expect conspicuous staining in bronchial respiratory epithelium and cerebral cortical neurons (HPA tissue IHC: High). UniProt also records cytoplasmic and spindle localization in specific contexts (UniProt Q8N163: subcellular location). CCAR2 has no transmembrane segment, so a membrane outline is not its expected pattern (UniProt Q8N163: topology). HPA rates the tissue IHC profile Enhanced for agreement with RNA expression (HPA tissue IHC: reliability).
| Distinct nuclear chromogen in bronchial respiratory epithelial cells, with nuclei identifiable by counterstain (HPA tissue IHC: High in bronchus). | This fits the reported ubiquitous nuclear profile (HPA tissue IHC). Judge whether staining follows individual nuclei and the tissue architecture; HPA's High category describes the reported cell population, not a required chromogen darkness for every run (HPA tissue IHC; general IHC practice). |
| Predominantly membranous or uniformly cytoplasmic staining, with little nuclear signal. | A membrane outline conflicts with CCAR2's lack of a transmembrane segment (UniProt Q8N163: topology). Cytoplasmic localization is reported with MCC or during UV-induced apoptosis, but those contexts cannot be inferred from appearance alone (UniProt Q8N163: subcellular location). Review controls before assigning this pattern to CCAR2 (general IHC practice). |
| Strong staining in lung alveolar cells while an expected positive cell population lacks nuclear signal. | HPA reports CCAR2 as Not detected in alveolar cells, despite its broader ubiquitous nuclear profile (HPA tissue IHC: lung; profile). This mismatch raises possible cross-reactivity or endogenous detection activity; compare a known-positive section and detection controls before interpreting it as a biological exception (general IHC practice). |
| Diffuse chromogen covers nuclei, cytoplasm and surrounding tissue without clear cell boundaries. | Diffuse background prevents a reliable nuclear call (general IHC practice; HPA tissue IHC: nuclear profile). Check the no-primary control and background in tissue compartments; excess detection reagent, incomplete blocking or insufficient washing are general possibilities, not documented CCAR2-specific effects (general IHC practice). |
| No nuclear signal in bronchial respiratory epithelium or another HPA High cell population. | A blank known-positive population conflicts with the reported tissue pattern (HPA tissue IHC: bronchus, respiratory epithelial cells, High). First assess section integrity, positive-control performance and the staining run (general IHC practice). One negative section cannot establish that CCAR2 is absent from the sample. |
| Cell population and reference tissue | HPA reports High staining in bronchial respiratory epithelium and cerebral cortical neurons, Low staining in pancreatic exocrine glandular cells, and Not detected in lung alveolar cells (HPA tissue IHC). Compare like cell populations; neighboring cells need not share an intensity category. |
| Antibody validation | HPA lists HPA019907 and HPA019943 as IHC Enhanced, and CAB072827 as IHC Supported (HPA antibodies). These are validation summaries for those antibodies, not proof that every reagent or staining run will reproduce the tissue profile (HPA antibodies; general IHC practice). |
| Isoforms and protein modification | UniProt lists two CCAR2 isoforms and modified residues, including phosphorylation, acetylation and methylation (UniProt Q8N163). The payload gives no antibody epitope or IHC comparison across these forms, so their effect on staining cannot be predicted. |
| IF/ICC Q: Where should fluorescence appear? | A: HPA reports nucleoplasm and nuclear bodies as enhanced locations in ICC-IF images (HPA subcellular ICC-IF). This supports a nuclear IF/ICC interpretation; it does not define an IHC antigen retrieval method, dilution or chromogenic intensity. |
| Situation | Likely cause | Next action |
|---|---|---|
| Known-positive bronchial epithelium is blank. | The result disagrees with HPA's High call for respiratory epithelial cells (HPA tissue IHC); a failed staining or detection step is possible (general IHC practice). | Check that a same-run positive control stained, then review antibody application, detection reagents and counterstain. Optimize antigen retrieval against a positive control if needed; no CCAR2-specific retrieval condition or fixation sensitivity is supplied (general IHC practice). |
| Only lung alveolar cells stain strongly. | HPA reports alveolar cells as Not detected (HPA tissue IHC: lung). Strong isolated staining may reflect cross-reactivity or endogenous detection activity (general IHC practice). | Verify alveolar cell identity on the counterstained section; compare an expected positive population and a no-primary control before assigning the chromogen to CCAR2 (general IHC practice). |
| A crisp membrane rim dominates the slide. | CCAR2 has no transmembrane segment, and HPA describes a ubiquitous nuclear IHC profile (UniProt Q8N163: topology; HPA tissue IHC). | Inspect the no-primary control and repeat with an IHC-validated antibody if needed. Score nuclear signal separately from the membrane pattern (HPA antibodies: IHC validation; general IHC practice). |
| Cytoplasmic staining dominates while nuclei appear weak. | UniProt reports cytoplasmic CCAR2 in specified contexts, including MCC presence and UV-induced apoptosis; the slide alone does not establish either context (UniProt Q8N163: subcellular location). | Confirm nuclear staining in a same-run HPA High reference population, then evaluate background and antibody specificity before interpreting cytoplasmic signal (HPA tissue IHC; general IHC practice). |
| Chromogen is diffuse across the section. | Background can obscure the nuclear profile reported by HPA (HPA tissue IHC; general IHC practice). Incomplete blocking or washing is a general workflow possibility (general IHC practice). | Compare the no-primary control, check wash and blocking steps, and adjust antibody or detection conditions empirically with a positive reference section (general IHC practice). |
| A low-staining population is judged negative because it lacks strong chromogen. | HPA distinguishes Low populations, including pancreatic exocrine glandular cells, from Not detected alveolar cells (HPA tissue IHC). | Score the named cell population and its nuclear compartment against a same-run positive control; report weak or indeterminate staining separately from absent staining (HPA tissue IHC; general IHC practice). |
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.
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Cerebellum | Cells in molecular layer | High | Protein (IHC) | HPA → |
| Cerebral cortex | Neuronal cells | High | Protein (IHC) | HPA → |
| Epididymis | Glandular cells | High | Protein (IHC) | HPA → |
| Esophagus | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Lung | Alveolar cells | Not detected | Protein (IHC) | HPA → |
Troubleshoot CCAR2 staining in paraffin sections by checking retrieval, compartment, controls and scoring against the expected nuclear pattern (HPA: tissue IHC).
The catalog antibodies cover paraffin-section IHC in human cancer tissue and mouse brain, plus IF/ICC in U20S cells (A03412-1 and A30523 image captions).
A03412-1 has IHC images from human gall bladder adenosquamous carcinoma, liver cancer, lung cancer, and mouse brain, plus an IF/ICC image from U20S cells (A03412-1 image captions). A30523 has an IHC image from paraffin-embedded human liver cancer and lists IF/ICC as applications without an IF image (A30523 image caption; catalog applications).
Which to pick: For tissue IHC across the pictured samples, choose A03412-1; its IHC images document paraffin sections from human cancers and mouse brain (A03412-1 IHC image captions). For IF/ICC, choose A03412-1 when a pictured cell staining example matters; A30523 also lists IF/ICC and is described as polyclonal, but has no IF image in the payload (A03412-1 IF image caption; A30523 catalog applications and dilution record). For cross-species planning, A03412-1 lists human, mouse, rat, and monkey reactivity, while A30523 lists human, mouse, and rat; the IHC captions report paraffin sections but do not report the fixative (catalog reactivity; A03412-1 and A30523 IHC image captions).