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- Table of Contents
Plan APOBEC3G staining in paraffin sections with the IHC-validated antibody at 0.5–1 μg/ml (datasheet M00708). Assess the cytoplasmic signal seen in several tissues, including immune cells (HPA tissue IHC).
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
| Expected localisation | Cytoplasmic staining in several tissues (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic signal, including in immune cells (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet M00708) | |
| Positive control | Appendix+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
| Fixation | Keep fixation conditions consistent across sections. (standard IHC practice; not target-specific) | |
| Caveat | Antibody staining and RNA expression have medium consistency (HPA tissue IHC) | |
| Regulation | Lymphoid tissue enhanced at the RNA level (HPA tissue RNA) | |
| Isoform / epitope | 2 isoforms (1, 3); epitope coverage is unknown (UniProt) |
The catalog antibody uses EDTA pH 8.0 heat retrieval (datasheet M00708). The published IHC protocols below cover ovarian carcinoma and rhesus macaque lymph node (PMC5026552; PMC4418221).
| Sample | Paraffin-embedded human intestinal cancer tissue; fixative not specified (datasheet M00708) |
| Fixation | Image fixative and duration unreported (datasheet M00708); 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 M00708); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet M00708) |
| Primary antibody | Mouse monoclonal (clone 6C2) anti-APOBEC3G, 0.5-1μg/ml (datasheet M00708) |
| Primary incubation | Overnight at 4 °C (datasheet M00708) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet M00708) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | APOBEC3G-positive staining in lymphoid tissue of appendix (HPA tissue IHC: Medium). HPA tissue profile: Cytoplasmic expression in several tissues, including immune cells. No signal in the no-primary control. |
APOBEC3G should stain mainly in the cytoplasm, with a small nuclear component possible (UniProt Q9HC16: mainly cytoplasmic; small amount nuclear). In paraffin sections, look first at lymphoid cells in appendix, lymph node or tonsil, and cells in splenic red pulp (HPA tissue IHC: Medium). The tissue IHC profile is rated Enhanced, with medium consistency between antibody staining and RNA expression (HPA tissue IHC: reliability). APOBEC3G has no transmembrane segment (UniProt Q9HC16: topology).
| Cytoplasmic staining in lymphoid cells or splenic red-pulp cells. | This fits the reported IHC pattern: lymphoid cells in appendix, lymph-node germinal centers and tonsillar non-germinal centers, and splenic red-pulp cells have Medium staining (HPA tissue IHC). Compare the stained cell population with adjacent unstained cells before scoring the section. |
| Predominantly nuclear, membrane-rim or extracellular staining. | Recheck the pattern before calling it APOBEC3G. A small nuclear component is plausible, but mainly cytoplasmic localisation is expected (UniProt Q9HC16: subcellular location). A dominant membrane or extracellular pattern lacks support from its reported localisation and topology (UniProt Q9HC16: no transmembrane segment). |
| Strong staining of adipocytes or bronchial respiratory epithelium. | These cell populations were Not detected in the supplied tissue IHC profile (HPA tissue IHC). Consider nonspecific binding or endogenous detection activity, especially if the expected lymphoid-cell pattern is absent; staining in an unexpected cell type alone does not establish cross-reactivity. |
| Uniform haze over cells, stroma and empty spaces. | This obscures the cell-specific cytoplasmic pattern reported for APOBEC3G (HPA tissue IHC: profile). In chromogenic IHC, assess background with an appropriate negative control and review blocking, washing and detection conditions (general IHC practice). |
| No staining in lymphoid cells of an otherwise interpretable positive tissue. | Appendix lymphoid cells, lymph-node germinal-center cells and tonsillar non-germinal-center cells show Medium staining in the HPA profile (HPA tissue IHC). Absence of signal warrants a run-control check, although that reference does not guarantee staining in every cell or section. |
| Compartment and cell population | Score localisation within identified cells, rather than staining anywhere in a positive organ. APOBEC3G is mainly cytoplasmic (UniProt Q9HC16), while HPA reports Medium staining in specified lymphoid and splenic red-pulp cell populations (HPA tissue IHC). |
| Tissue choice and reference strength | Lymphoid tissue is RNA tissue-enhanced, and several lymphoid populations show Medium protein staining (HPA tissue IHC). The IHC profile is Enhanced but has only medium consistency with RNA data (HPA tissue IHC: reliability); use the observed cell-level pattern as the comparison. |
| Antibody validation | The IHC-validated antibody HPA001812 has an Enhanced IHC status; HPA073637 has ICC Approved status and no supplied IHC status (HPA antibodies). These labels support different applications and do not establish that the two antibodies will produce identical paraffin-section patterns. |
| IF/ICC Q&A: Is nuclear signal expected? | Yes, a small nuclear component is possible (UniProt Q9HC16: subcellular location). HPA reports nucleoplasm and cytosol in ICC-IF, both uncertain because the localisation assessment uses antibodies targeting proteins from multiple genes (HPA subcellular ICC-IF). Assess IF/ICC on its own guide page. |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in a reference-positive lymphoid area. | The staining run may have failed, or the sampled cells may not match the HPA-positive population (HPA tissue IHC: Medium in specified lymphoid cells). | Confirm cell identity and the run control, then review the catalog antibody's IHC-P conditions and detection steps (general IHC practice). |
| Predominantly nuclear staining. | Some nuclear APOBEC3G is reported, but mainly cytoplasmic localisation is expected (UniProt Q9HC16). A nuclear-only result needs corroboration. | Compare nuclear and cytoplasmic signal in the same cells, then check a suitable negative control and an HPA-positive tissue pattern (general IHC practice; HPA tissue IHC). |
| Strong adipocyte or bronchial epithelial staining. | Those cell types are Not detected in the supplied HPA examples (HPA tissue IHC); nonspecific binding or endogenous detection activity is possible. | Check negative controls and the detection system, then compare with staining in a reported Medium-positive cell population (general IHC practice; HPA tissue IHC). |
| Diffuse brown background hides cell boundaries. | Background from binding or detection can prevent cell-level interpretation (general IHC practice); HPA describes a cytoplasmic tissue profile (HPA tissue IHC). | Inspect the negative control, washing and blocking steps; score only signal that remains distinguishable within the expected cells (general IHC practice). |
| A glandular sample stains while lymphoid tissue does not. | Glandular-cell staining can be legitimate: fallopian tube, prostate and seminal vesicle glandular cells are Medium in HPA (HPA tissue IHC). | Verify the sampled cell types and controls before treating the glandular result as nonspecific or the lymphoid result as a true negative (general IHC practice; HPA tissue IHC). |
| ICC-IF shows cytosolic and nucleoplasmic signal. | HPA lists both ICC-IF locations as uncertain; UniProt reports mainly cytoplasmic APOBEC3G with a small nuclear amount (HPA subcellular ICC-IF; UniProt Q9HC16). | Interpret the IF result within its own application and controls; do not use uncertain ICC-IF localisation alone to overturn the tissue IHC pattern (HPA subcellular ICC-IF; HPA tissue IHC). |
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium 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 |
|---|---|---|---|---|
| Appendix | Lymphoid tissue | Medium | Protein (IHC) | HPA → |
| Fallopian tube | Glandular cells | Medium | Protein (IHC) | HPA → |
| Lymph node | Germinal center cells | Medium | Protein (IHC) | HPA → |
| Prostate | Glandular cells | Medium | Protein (IHC) | HPA → |
| Seminal vesicle | Glandular cells | Medium | Protein (IHC) | HPA → |
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
| Caudate | Glial cells | Not detected | Protein (IHC) | HPA → |
| Cerebellum | Cells in granular layer | Not detected | Protein (IHC) | HPA → |
Troubleshoot APOBEC3G staining in paraffin sections by checking retrieval, cell identity, compartment, controls, and scoring before interpreting chromogenic signal.
Anti-APOBEC3G antibodies have IHC images from human paraffin sections (M00708 image captions) and IF images from human cell preparations (M00708 and PB9985 image captions).
M00708 is listed for human IHC and IF, with images from paraffin sections of intestinal cancer, testis cancer and tonsil, plus MCF7 cells (catalog applications and reactivity; M00708 image captions). PB9985 is listed for IF/ICC and shows staining in A431 cells; its catalog lists human, mouse and rat reactivity (catalog applications and reactivity; PB9985 IF caption).
Which to pick: For tissue IHC, choose mouse monoclonal M00708: its IHC captions document paraffin sections and EDTA pH 8 retrieval, but do not report the fixative (catalog host and clone; M00708 IHC captions). For IF/ICC, either SKU is listed; M00708 is mouse monoclonal 6C2 with an MCF7 IF image, while PB9985 is rabbit with an A431 IF image (catalog host, clone and applications; IF captions). For mouse or rat samples, PB9985 is the catalog-listed option for reactivity, though its supplied IF image documents A431 cells only (PB9985 catalog reactivity; PB9985 IF caption).