APOBEC3G / DNA dC->dU-editing enzyme APOBEC-3G · IHC design guide

Design Immunohistochemistry for APOBEC3G

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).

Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
Immunohistochemistry protocol sheet for APOBEC3G (IHC for APOBEC3G): expected localisation Cytoplasmic staining in several tissues (HPA tissue IHC), antibody M00708, validated IHC image, and IHC protocol steps
Printable APOBEC3G IHC protocol sheet — expected localisation Cytoplasmic staining in several tissues (HPA tissue IHC), antibody M00708, controls and protocol steps. Open the full APOBEC3G IHC guide →

APOBEC3G 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 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
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 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)
Section 1

Recommended APOBEC3G IHC & IF Protocols

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).

Recommended immunohistochemistry (IHC-P) protocol parameters
SampleParaffin-embedded human intestinal cancer tissue; fixative not specified (datasheet M00708)
FixationImage fixative and duration unreported (datasheet M00708); verify before use.
Sectioning4–5 µm sections on charged slides (standard)
DeparaffinisationXylene, graded ethanol series to water (standard)
Antigen retrievalHeat retrieval: EDTA pH 8.0 (datasheet M00708); 20 min, 95–100 °C (standard)
Peroxidase block3% H2O2, 10 min, room temperature (standard)
Blocking10% goat serum (datasheet M00708)
Primary antibodyMouse monoclonal (clone 6C2) anti-APOBEC3G, 0.5-1μg/ml (datasheet M00708)
Primary incubationOvernight at 4 °C (datasheet M00708)
DetectionStreptavidin-biotin complex (SABC), DAB chromogen (datasheet M00708)
CounterstainHematoxylin, blue, dehydrate and mount (standard)
Expected resultAPOBEC3G-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.
💡Decision noteStart with EDTA pH 8.0 heat retrieval for the catalog antibody (datasheet M00708). Use the reported retrieval conditions when reproducing either published protocol (PMC5026552; PMC4418221).
Section 2

What Is the Expected APOBEC3G Staining Pattern?

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).

What am I looking at on my slide?
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.
💡Expected APOBEC3G appearanceCall a convincing positive result when the relevant lymphoid or splenic red-pulp cells show discernible, mainly cytoplasmic staining at a level comparable to the HPA Medium pattern; widespread haze or dominant membrane staining is suspect (HPA tissue IHC: Medium; UniProt Q9HC16: localisation and topology).
How each factor affects the staining
Compartment and cell populationScore 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 strengthLymphoid 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 validationThe 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.
Why is my staining missing, weak or wrong?
SituationLikely causeNext 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).

Sample controls for APOBEC3G IHC & IF

🧪Run lymph node first and expect germinal center cells to stain (HPA: Medium in lymph node germinal center cells); use adipose tissue as the negative comparator, with adipocytes expected to lack staining (HPA: Not detected in adipose tissue adipocytes). On the positive slide, use cells outside the stained germinal centers as an internal background reference only after confirming they are unstained; HPA does not establish that every other cell type there is negative.
Positive control tissue: Appendix (Lymphoid tissue, HPA Medium)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show APOBEC3G in A-431, RT-4, U2OS, with annotated localisation: Nucleoplasm (uncertain), Cytosol (uncertain) (HPA subcellular).
Technical controls: Include a no-primary (secondary-only) slide, a concentration-matched mouse isotype control for the mouse catalog antibody (selected-SKU caption: mouse primary), and an APOBEC3G knockout specimen or validated peptide-block control if available. For lymph node, quench endogenous peroxidase and check for endogenous biotin before interpreting DAB signal from the biotin-based detection system (selected-SKU caption: biotinylated secondary, SABC and DAB).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported in the supplied evidence, and the selected-SKU paraffin-section caption does not report a fixative (selected-SKU caption: fixative not stated). The documented IHC workflow uses heat retrieval in EDTA at pH 8.0, but the evidence does not establish that retrieval is required or that frozen sections or IF are easier (selected-SKU caption: heat-mediated EDTA retrieval; HPA subcellular: ICC-IF locations uncertain). In lymph node, check whether signal follows germinal center cells rather than background from endogenous peroxidase or biotin in the biotin-based chromogenic workflow (HPA: Medium in lymph node germinal center cells; selected-SKU caption: SABC/DAB detection).

HPA tissue IHC evidence for APOBEC3G

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.

Positive expression · recommended positive controls

TissueCell typeLevelEvidenceSource
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 →

Undetected expression · recommended negative controls

TissueCell typeLevelEvidenceSource
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 →
Section 3

Advanced APOBEC3G IHC Tips

Troubleshoot APOBEC3G staining in paraffin sections by checking retrieval, cell identity, compartment, controls, and scoring before interpreting chromogenic signal.

What retrieval should I try when APOBEC3G staining is weak?
Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections (datasheet M00708). The selected image used this retrieval before 1 μg/mL primary antibody overnight at 4°C, providing a documented starting condition (datasheet M00708). Compare a positive-control section and a no-primary control in the same run before changing retrieval conditions (standard IHC practice). If staining remains weak, test a shorter and a longer heating interval on adjacent sections while keeping antibody concentration and detection constant (standard IHC practice). Assess tissue damage and background alongside signal, because stronger staining alone does not establish specificity (standard IHC practice).
Could fixation explain weak or uneven APOBEC3G staining?
Target-specific fixation sensitivity is unknown: the selected paraffin-section caption does not state a fixative (datasheet M00708). Record the actual fixative, fixation duration, section thickness, and processing history for every specimen being compared (standard IHC practice). If a control stains but a test block does not, compare blocks processed under matched conditions before attributing the difference to APOBEC3G expression (standard IHC practice). Use adjacent sections and the documented EDTA pH 8.0 retrieval to check reproducibility without changing several variables at once (datasheet M00708; standard IHC practice). Do not infer fixation tolerance from tissue staining patterns or APOBEC3G topology and phosphorylation sites (HPA tissue IHC; UniProt Q9HC16).
Which staining compartment should count as APOBEC3G positive?
Expect predominantly cytoplasmic staining, with a smaller possible nuclear component; APOBEC3G is also reported in cytoplasmic P-bodies (UniProt Q9HC16 subcellular location). Score cytoplasmic and nuclear signal separately rather than combining them into one positive call (UniProt Q9HC16 subcellular location; standard IHC practice). Compare each compartment with a no-primary control and with the morphology of the stained cell (standard IHC practice). HPA reports cytoplasmic expression across several tissues, including immune cells, while its nucleoplasm and cytosol IF assignments are marked uncertain (HPA tissue IHC; HPA subcellular). A crisp membrane-only pattern needs additional specificity checks because APOBEC3G has no transmembrane segment (UniProt Q9HC16 topology).
How should isoforms and epitope uncertainty affect antibody selection?
The record lists 2 APOBEC3G isoforms, numbered 1 and 3, but the supplied caption does not identify the M00708 epitope (UniProt Q9HC16 isoforms; datasheet M00708). Request or inspect an epitope map before claiming that a stained cell expresses a particular isoform (standard IHC practice). APOBEC3G contains deaminase domains at residues 29–138 and 214–328, and reported phosphorylation sites at residues 32 and 218 (UniProt Q9HC16 domains and modified residues). Those features do not establish whether fixation or retrieval exposes this antibody’s unknown epitope (datasheet M00708; standard IHC practice). If isoform specificity matters, validate it with independently characterized material and a reagent whose binding region is known (standard IHC practice).
How can IF help resolve an ambiguous chromogenic pattern?
Use IF/ICC as a separate localization check, while judging this page’s antibody against its documented paraffin-section IHC example (datasheet M00708). Multiplex APOBEC3G with a validated marker for the cell population under investigation, and include single-stain controls to check channel bleed-through (standard IF practice). Choose a fluorophore channel with low measured tissue autofluorescence and compare it with an unstained section before calling faint signal positive (standard IF practice). Because APOBEC3G is mainly cytoplasmic and can enter the nucleus, permeabilize sufficiently to access intracellular epitopes and assess both compartments (UniProt Q9HC16 subcellular location; standard IF practice). Treat HPA’s nucleoplasm and cytosol IF assignments cautiously because both are marked uncertain (HPA subcellular).
What should I change when DAB background obscures APOBEC3G?
Run no-primary and detection-only controls to locate background from secondary reagents or the chromogenic system (standard IHC practice). The selected example used 10% goat serum blocking, a biotinylated goat anti-mouse secondary for 30 minutes at 37°C, and streptavidin–biotin detection with DAB (datasheet M00708). Include an endogenous peroxidase block and evaluate endogenous biotin where a biotin-based system is used (standard IHC practice). If diffuse staining persists, titrate the primary around the documented 1 μg/mL condition and adjust wash stringency on matched sections (datasheet M00708; standard IHC practice). Compare background in cells reported as unstained, such as adipocytes, without treating those reference observations as an absolute negative control (HPA tissue IHC).
How should APOBEC3G IHC be quantified across specimens? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, because APOBEC3G is mainly cytoplasmic and HPA reports staining in several immune-cell populations (UniProt Q9HC16 subcellular location; HPA tissue IHC). For identifiable cells, report the percentage positive and an H-score from intensity categories; keep nuclear and cytoplasmic scores separate (standard IHC practice). For dispersed stained cells, report positive-cell density per mm² of evaluable tissue (standard IHC practice). Normalize counts to the relevant cell population or evaluable tissue area, and exclude folds, edges, and necrotic regions by predefined rules (standard IHC practice). Apply the same thresholds, imaging settings, and control sections across batches, and report how background was subtracted (standard IHC practice).
How do I distinguish true APOBEC3G signal from artefact?
A credible result shows reproducible cellular staining that fits APOBEC3G’s mainly cytoplasmic localization, with a possible smaller nuclear component (UniProt Q9HC16 subcellular location). Check cell identity before assigning positive signal: HPA reports medium staining in lymph-node germinal-center cells and spleen red-pulp cells, but no detected staining in adipocytes (HPA tissue IHC). Treat edge accentuation, necrotic deposits, and signal in no-primary controls as potential artefacts requiring resolution (standard IHC practice). A membrane-only pattern warrants scrutiny because APOBEC3G has no transmembrane segment; brown deposits may also arise from endogenous peroxidase in a DAB workflow (UniProt Q9HC16 topology; standard IHC practice). Finally, staining establishes antigen detection under the assay conditions, not APOBEC3G enzymatic activity or antiviral function (UniProt Q9HC16 function; standard IHC practice).
Boster reagents

Best APOBEC3G / DNA dC->dU-editing enzyme APOBEC-3G IHC Antibodies

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).

Real IHC data IHC analysis of APOBEC3G using anti-APOBEC3G antibody (M00708). APOBEC3G was detected in paraffin-embedded section of human intestinal cancer tissue. Heat mediated antigen retrieval was performed in EDTA buffer (pH8.0, epitope retrieval solution). The tissue section was blocked with 10% goat serum. The tissue section was then incubated with 1μg/ml mouse anti-APOBEC3G Antibody (M00708) overnight at 4°C. Biotinylated goat anti-mouse IgG was used as secondary antibody and incubated for 30 minutes at 37°C. The tissue section was developed using Strepavidin-Biotin-Complex (SABC) (Catalog # SA1021) with DAB as the chromogen.
Anti-APOBEC3G Antibody ® (monoclonal, 6C2)
Cat # M00708
Real IF data IF analysis of APOBEC3G using anti-APOBEC3G antibody (PB9985). APOBEC3G was detected in an immunocytochemical section of A431 cells. Enzyme antigen retrieval was performed using IHC enzyme antigen retrieval reagent (AR0022) for 15 mins. The cells were blocked with 10% goat serum. And then incubated with 5 μg/mL rabbit anti-APOBEC3G Antibody (PB9985) overnight at 4°C. DyLight®488 Conjugated Goat Anti-Rabbit IgG (BA1127) was used as secondary antibody at 1:500 dilution and incubated for 30 minutes at 37°C. The section was counterstained with DAPI. Visualize using a fluorescence microscope and filter sets appropriate for the label used.
Anti-APOBEC3G Antibody ®
Cat # PB9985

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).

Each figure is that product's own IHC / IF validation image from its datasheet.

References

  1. UniProt Consortium. UniProt entry Q9HC16 (ABC3G_HUMAN, DNA dC->dU-editing enzyme APOBEC-3G).
  2. Human Protein Atlas. APOBEC3G tissue IHC expression (reliability: Enhanced).
  3. Human Protein Atlas. APOBEC3G subcellular location (ICC-IF): Localized to the nucleoplasm and cytosol. Caution: Based on antibodies targeting proteins from multiple genes..
  4. Human Protein Atlas. APOBEC3G antibody validation summary (2 antibodies).
  5. APOBEC3G Expression Correlates with T-Cell Infiltration and Improved Clinical Outcomes in High-grade Serous Ovarian Carcinoma. Clinical cancer research : an official journal of the American Association for Cancer Research 2016 — PMC5026552.
  6. Evaluation of CD4(+) cells infiltration as a prognostic factor in cervical intraepithelial neoplasia 2. Journal of gynecologic oncology 2023 — PMC9807366.
  7. Type I interferon responses in rhesus macaques prevent SIV infection and slow disease progression. Nature 2014 — PMC4418221.
  8. Primary mucosal melanomas of the head and neck are characterised by overexpression of the DNA mutating enzyme APOBEC3B. Histopathology 2023 — PMC10107945.
  9. PubMed PMID:14557625 — UniProt-cited evidence.
  10. PubMed PMID:14702039 — UniProt-cited evidence.
  11. PubMed PMID:15461802 — UniProt-cited evidence.