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LAP3 / Cytosol aminopeptidase · IHC design guide
Design Immunohistochemistry for LAP3
Plan chromogenic LAP3 IHC in paraffin sections using the catalog antibody’s documented tissue workflow (datasheet A01921-1). Compare cytoplasmic staining with high expression in hepatocytes and kidney proximal tubules (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
LAP3 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 | Cytoplasm in most tissues; brain and muscle are exceptions (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic in many cells; high in hepatocytes and renal tubules (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A01921-1) | |
| Positive control | Kidney+4 more · see all | |
| Negative control | Caudate+4 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 | Staining has medium consistency with RNA expression (HPA tissue IHC) | |
| Regulation | Staining regulation is unreported (UniProt) | |
| Isoform / epitope | 2 isoforms; epitope coverage is unspecified (UniProt) |
Section 1
Recommended LAP3 IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet: A01921-1) is accompanied by three published LAP3 IHC protocols (PMC5790517; PMC10882082; PMC9977676).
| Sample | Paraffin-embedded human ovarian serous adenocarcinoma tissue; fixative not specified (datasheet A01921-1) |
| Fixation | Image fixative and duration unreported (datasheet A01921-1); 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 A01921-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A01921-1) |
| Primary antibody | Rabbit anti-LAP3, 2-5 μg/ml (datasheet A01921-1) |
| Primary incubation | Overnight at 4 °C (datasheet A01921-1) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A01921-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | LAP3-positive staining in proximal tubules (microvilli) of kidney (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in essentially all tissues, except for brain and muscle tissue. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA at pH 8.0 for the catalog antibody (datasheet: A01921-1). A published paraffin-section protocol uses Tris/borate/EDTA at pH 8–8.5 (PMC5790517).
Section 2
What Is the Expected LAP3 Staining Pattern?
LAP3 is a cytoplasmic protein with no transmembrane segment (UniProt P28838: subcellular location and topology). In paraffin-section IHC, expect cytoplasmic staining across many tissues, with high staining reported in kidney proximal-tubule microvilli, liver hepatocytes, lung endothelial cells, stomach glandular cells and late spermatids (HPA: tissue IHC). HPA rates the tissue profile Enhanced and describes medium consistency between antibody staining and RNA expression (HPA: reliability description).
| Cytoplasmic staining in hepatocytes or stomach glandular cells; signal may vary between cells (HPA: High in both cell types). | This fits the reported IHC distribution and UniProt location (HPA: tissue IHC; UniProt P28838: Cytoplasm). Judge localisation alongside the cell identity; staining intensity alone does not establish specificity (general IHC practice). |
| Strong nuclear or sharply membrane-confined signal dominates the section. | That compartment conflicts with the reported cytoplasmic pattern and lack of a transmembrane segment (HPA: tissue IHC; UniProt P28838: topology). Treat it as suspect and check controls and detection conditions (general IHC practice). |
| Strong staining is confined to cardiomyocytes, skeletal myocytes or glial cells in sampled brain regions. | Those cells are reported as Not detected in the corresponding HPA sections (HPA: heart muscle, skeletal muscle, caudate and hippocampus). Consider antibody cross-reactivity or endogenous detection activity; confirm cell identity and controls (general IHC practice). |
| Weak, diffuse color covers tissue, stroma and blank areas without a clear cellular pattern. | This is difficult to score as LAP3 because the expected pattern is cellular and mainly cytoplasmic (HPA: tissue IHC; UniProt P28838: Cytoplasm). Nonspecific binding or detection background are possible (general IHC practice). |
| No staining appears in an otherwise interpretable liver or kidney section. | HPA reports High staining in hepatocytes and proximal-tubule microvilli (HPA: liver and kidney). Review tissue preservation, retrieval, primary-antibody application and detection controls before calling the sample negative (general IHC practice). |
💡Expected LAP3 appearanceCall a result positive when staining is predominantly cytoplasmic in an HPA-supported cell type, especially high in hepatocytes or kidney proximal-tubule microvilli; dominant nuclear staining or strong signal restricted to HPA Not detected cells is suspect (HPA: tissue IHC; UniProt P28838: Cytoplasm).
| Cell type and tissue | LAP3 staining is broad but uneven: HPA reports High in hepatocytes, lung endothelial cells and stomach glandular cells, Medium in adrenal, appendix and breast glandular cells, and Not detected in several brain and muscle cell populations (HPA: tissue IHC). Compare like cell types when scoring. |
| Subcellular location | UniProt places LAP3 in the cytoplasm and reports no transmembrane segment or signal peptide (UniProt P28838: location and topology). HPA tissue IHC is cytoplasmic overall, while kidney proximal-tubule microvilli are specifically reported High (HPA: tissue IHC). |
| Antibody validation | Both listed antibodies have Enhanced IHC status (HPA: HPA029606 and HPA029607). HPA describes Enhanced IHC as a pattern supported by independent antibodies or orthogonal data (HPA: antibody-validation summary); it does not make every stain in every specimen specific. |
| Isoforms and processing | UniProt lists two isoforms and a chain spanning residues 1–519, with no annotated signal peptide or propeptide (UniProt P28838: isoforms and processing). The supplied HPA IHC profile does not assign its tissue pattern to either isoform (HPA: tissue IHC). |
| IF/ICC cross-check | Q: What localisation should IF/ICC show? A: Mainly cytosol; HPA also approves calyx, mid piece and principal piece localisation in its subcellular record (HPA: ICC-IF). This supports a compartment check, while the IHC tissue profile governs paraffin-section interpretation (HPA: tissue IHC). |
| Retrieval and detection conditions | Antigen retrieval and detection conditions can alter IHC signal and background in general (general IHC practice). Target-specific fixation sensitivity or an optimal retrieval condition is unreported in the supplied UniProt and HPA records; avoid inferring either from staining levels. |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in liver hepatocytes or kidney proximal tubules. | A technical failure is possible because both are reported High (HPA: liver and kidney); the supplied records do not identify a LAP3-specific fixation effect. | Check section quality, retrieval, primary-antibody application and detection using appropriate controls (general IHC practice). Reassess the expected cells before scoring a negative result (HPA: tissue IHC). |
| Dominant nuclear staining accompanies little cytoplasmic signal. | The pattern conflicts with the reported cytoplasmic localisation (UniProt P28838: Cytoplasm; HPA: tissue IHC). Nonspecific antibody or detection signal is possible (general IHC practice). | Compare a positive tissue and a primary-omission control, then review antibody dilution and detection conditions (general IHC practice). Interpret only a reproducible, cell-appropriate pattern. |
| Strong signal appears in cardiomyocytes or skeletal myocytes. | HPA reports Not detected in those cells (HPA: heart muscle and skeletal muscle). Cross-reactivity or endogenous detection activity could explain discordant color (general IHC practice). | Verify cell identity and examine a primary-omission control; address endogenous detection activity if that control is colored (general IHC practice). Compare with an HPA-supported positive tissue. |
| Color is diffuse across tissue and blank slide areas. | A noncellular pattern does not match cytoplasmic LAP3 staining (HPA: tissue IHC; UniProt P28838: Cytoplasm). Inadequate blocking, overly strong primary staining or detection background may contribute (general IHC practice). | Inspect primary-omission and reagent controls; optimize blocking, washing, antibody dilution and detection exposure as appropriate (general IHC practice). Score cells only after background is controlled. |
| Kidney staining looks apical rather than evenly cytoplasmic. | High proximal-tubule microvillar staining is specifically reported (HPA: kidney); apical signal in those cells need not indicate a membrane-spanning LAP3 protein (UniProt P28838: no transmembrane segment). | Confirm proximal-tubule morphology and compare adjacent cell types before rejecting the pattern (HPA: kidney; general IHC practice). Assess whether staining remains associated with cells. |
| Weak staining in squamous epithelium seems inconsistent with a strong liver control. | HPA lists squamous epithelial cells in oral mucosa, esophagus and vagina as Low, versus High hepatocyte staining (HPA: tissue IHC). This difference can be expected. | Score each tissue against its reported cell-specific level and verify the liver control and assay background (HPA: tissue IHC; general IHC practice). Avoid imposing one intensity threshold across tissues. |
Experiment evidence
IHC & IF images showing LAP3 staining
A01921-1 · IHCIHC analysis of LAP3 using anti-LAP3 antibody (A01921-1). LAP3 was detected in a paraffin-embedded section of human ovarian serous adenocarc
A01921-1 · IHCIHC analysis of LAP3 using anti-LAP3 antibody (A01921-1). LAP3 was detected in a paraffin-embedded section of human tonsil tissue. Heat medi
A01921-1 · IFIF analysis of LAP3 using anti-LAP3 antibody (A01921-1). LAP3 was detected in an immunocytochemical section of U2OS cells. Enzyme antigen re
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000002549-LAP3/tissue/cerebral+cortex#imid_7600440
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000002549-LAP3/tissue/colon#imid_7600382
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000002549-LAP3/tissue/liver#imid_7600383
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000002549-LAP3/tissue/kidney#imid_7600384
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA029606; green = LAP3, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA029606; green = LAP3, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for LAP3 IHC & IF
🧪Run kidney first: proximal tubules, including their microvilli, should stain (HPA: High in kidney proximal tubules). Use skeletal muscle myocytes as the negative tissue (HPA: Not detected); on the kidney slide, cells outside proximal tubules should show little or no specific chromogen, but their negative status is not established by the supplied HPA row.
Positive control tissue: Kidney (Proximal tubules (microvilli), HPA High)
Negative control tissue: Caudate (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show LAP3 in A-431, U-251MG, U2OS, ASC52telo, RPTEC/TERT1, Sperm, with annotated localisation: Cytosol (approved) (HPA subcellular).
Technical controls: Include no-primary (secondary-only) and concentration-matched rabbit IgG isotype controls (selected-SKU caption: rabbit primary antibody), plus LAP3-knockout tissue or cells as a biological negative (standard IHC practice). Check kidney sections for endogenous peroxidase activity before interpreting HRP/DAB staining (selected-SKU caption: HRP/DAB detection; standard IHC practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected-SKU paraffin-section caption does not state the fixative. That caption used heat-mediated retrieval in EDTA at pH 8.0; it does not establish whether retrieval is required under other conditions. The supplied evidence does not establish that frozen sections or IF are easier; kidney endogenous peroxidase can complicate chromogenic interpretation (selected-SKU caption: HRP/DAB detection; standard IHC practice).
HPA tissue IHC evidence for LAP3
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
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Kidney | Proximal tubules (microvilli) | High | Protein (IHC) | HPA → |
| Liver | Hepatocytes | High | Protein (IHC) | HPA → |
| Lung | Endothelial cells | High | Protein (IHC) | HPA → |
| Stomach | Glandular cells | High | Protein (IHC) | HPA → |
| Testis | Elongated or late spermatids | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Caudate | Glial cells | Not detected | Protein (IHC) | HPA → |
| Cerebellum | Cells in granular layer | Not detected | Protein (IHC) | HPA → |
| Heart muscle | Cardiomyocytes | Not detected | Protein (IHC) | HPA → |
| Hippocampus | Glial cells | Not detected | Protein (IHC) | HPA → |
| Skeletal muscle | Myocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced LAP3 IHC Tips
Troubleshoot LAP3 chromogenic IHC by checking retrieval, cytoplasmic localisation, controls and cell-level scoring; IF considerations are covered separately.
What should I change when LAP3 staining is weak after antigen retrieval?
Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A01921-1). The selected tissue image used this retrieval before incubation with 2 μg/ml antibody overnight at 4°C; its fixative was not reported (A01921-1 tissue-IHC caption). Keep section thickness, heating and cooling consistent across a comparison series, then check whether cytoplasmic signal improves in a positive reference section (standard IHC practice; UniProt P28838 localisation). If staining remains weak, test a different retrieval buffer or pH on adjacent sections while holding antibody concentration and detection constant, and compare tissue preservation and background (standard IHC practice).
How should I troubleshoot weak staining when the tissue fixative is unknown?
Record the fixative and fixation duration for each specimen before comparing LAP3 staining, because fixation can change antigen accessibility in paraffin sections (standard IHC practice). Target-specific fixation sensitivity is unknown: the selected LAP3 image identifies a paraffin section but does not state its fixative (A01921-1 tissue-IHC caption). Do not infer a preferred fixative from LAP3 cytoplasmic localisation, modified residues or tissue staining patterns (UniProt P28838; HPA tissue IHC). Compare differently fixed material only with matched processing, EDTA retrieval at pH 8.0, detection and a reference section; interpret any difference as a processing effect until separately validated (datasheet A01921-1; standard IHC practice).
Where should credible LAP3 signal appear in a paraffin section?
Look first for staining within cell cytoplasm, consistent with LAP3's annotated cytoplasmic location and approved cytosolic localisation (UniProt P28838; HPA subcellular). LAP3 has no annotated transmembrane segment, so a dominant crisp membrane rim warrants a specificity or staining review (UniProt P28838 topology; standard IHC practice). Hepatocytes and kidney proximal tubules provide examples of high tissue staining, while cardiomyocytes and skeletal myocytes are reported as not detected (HPA tissue IHC). Evaluate those patterns by cell type on the same section, and check morphology and a negative reagent control before attributing isolated nuclear, stromal or edge staining to LAP3 (standard IHC practice).
Can a discordant staining pattern reflect isoform or epitope differences?
LAP3 has 2 annotated isoforms, but the supplied evidence does not map the catalog antibody's epitope or establish which isoforms it detects in tissue (UniProt P28838; A01921-1 tissue-IHC caption). Its annotated chain spans residues 1–519, and the record lists modified residues including phosphoserine at 42 and 54 (UniProt P28838). Those annotations alone cannot establish that modification or isoform choice caused a staining difference (UniProt P28838; standard IHC interpretation). Check the antibody's epitope documentation and compare adjacent sections with an independently validated epitope reagent, using the same retrieval and scoring conditions before assigning an isoform-specific pattern (standard IHC practice).
How can I assess LAP3 by IF alongside a cell identity marker?
For an IF experiment, pair LAP3 with a marker that identifies the expected cell type, such as a validated proximal tubule identity marker when examining kidney (HPA tissue IHC; standard IF practice). Select spectrally separated fluorophores and place the weaker signal in a channel with low measured tissue autofluorescence; include single-stain and unstained controls (standard IF practice). Because LAP3 is cytosolic and has no transmembrane segment, choose permeabilisation that gives antibody access to the cytosol without losing morphology (UniProt P28838 topology and localisation; standard IF practice). Optimise IF fixation and permeabilisation on IF specimens; the paraffin-section caption provides no IF fixation conditions (A01921-1 tissue-IHC caption).
What checks distinguish LAP3 staining from chromogenic background?
Compare a no-primary control with the complete stain to identify signal from detection reagents or endogenous tissue activity (standard IHC practice). Include a peroxidase-blocking step before HRP detection and inspect whether DAB deposits also appear in the no-primary control; these are general chromogenic workflow checks (standard IHC practice). The selected LAP3 image used 2 μg/ml primary antibody overnight at 4°C and HRP/DAB detection (A01921-1 tissue-IHC caption). If diffuse staining persists, titrate the primary antibody and detection time on adjacent sections while retaining EDTA retrieval at pH 8.0, and judge improvement against cytoplasmic signal and preserved morphology (datasheet A01921-1; standard IHC practice).
How should I quantify LAP3 staining across tissue samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and analysis region before scoring, then report cytoplasmic LAP3 as an H-score, percentage of positive cells or positive-cell density per mm² (UniProt P28838 localisation; standard IHC practice). An H-score combines the percentages at intensity grades 0–3 into a 0–300 scale (standard IHC practice). Normalise cell counts to the number of eligible cells, or density to the measured viable tissue area, and exclude folds, torn edges and necrosis by a prespecified rule (standard IHC practice). Keep retrieval, imaging, thresholds and cell-type definitions consistent, since LAP3 staining varies among reported tissue cell populations (datasheet A01921-1; HPA tissue IHC; standard IHC practice).
When should an unexpected LAP3-positive cell be treated as artefact?
Treat reproducible cytoplasmic staining in morphologically intact cells as more credible than isolated nuclear or sharp membrane staining, given LAP3's cytosolic localisation and lack of a transmembrane segment (UniProt P28838; HPA subcellular). Check the cell's identity: HPA reports high staining in hepatocytes and kidney proximal tubules, but no detected staining in cardiomyocytes or skeletal myocytes (HPA tissue IHC). A signal confined to section edges or necrotic areas requires review for processing artefact, and DAB signal in a no-primary control raises concern about endogenous enzyme activity or detection background (standard IHC practice). Resolve a discordant result with adjacent sections, matched controls and independent antibody validation before calling a new LAP3 expression pattern (standard IHC practice).
Boster reagents
Best LAP3 / Cytosol aminopeptidase IHC Antibodies
A01921-1 has pictured IHC in human ovarian serous adenocarcinoma and tonsil paraffin sections, plus IF/ICC in U2OS cells (A01921-1 image captions).
Real IHC data
Anti-LAP3 Antibody ®
Cat # A01921-1
A01921-1 will render with pictured human paraffin-section IHC; its separate IF/ICC image shows U2OS cells (A01921-1 image captions). M01921 will render as a human-reactive IHC antibody without a supplied IHC image (catalog: M01921 applications, reactivity, image list).
Which to pick: For tissue IHC, choose A01921-1 when pictured human paraffin-section evidence matters: its captions report EDTA retrieval at pH 8.0 and 2 μg/ml primary antibody, but do not report the fixative (A01921-1 IHC captions). M01921 is a human-reactive rabbit monoclonal listed for IHC, with no supplied IHC image (catalog: M01921 host, clone, applications, reactivity, image list). For IF/ICC or a mouse or rat reactive antibody, choose A01921-1; its IF/ICC image is in U2OS cells, while its pictured tissue IHC is human only (catalog: A01921-1 applications and reactivity; A01921-1 image captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P28838 (AMPL_HUMAN, Cytosol aminopeptidase).
- Human Protein Atlas. LAP3 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. LAP3 subcellular location (ICC-IF): Mainly localized to the cytosol. In addition localized to the calyx, mid piece and principal piece..
- Human Protein Atlas. LAP3 antibody validation summary (2 antibodies).
- Cholesterol-induced leucine aminopeptidase 3 (LAP3) upregulation inhibits cell autophagy in pathogenesis of NAFLD. Aging 2022 — PMC9037261.
- Proteomic profiling of antibody-inducing immunogens in tumor tissue identifies PSMA1, LAP3, ANXA3, and maspin as colon cancer markers. Oncotarget 2018 — PMC5790517.
- Mitochondrial-related hub genes in dermatomyositis: muscle and skin datasets-based identification and in vivo validation. Frontiers in genetics 2024 — PMC10882082.
- Identifying the key genes of Epstein-Barr virus-regulated tumour immune microenvironment of gastric carcinomas. Cell proliferation 2023 — PMC9977676.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
- PubMed PMID:1908238 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for LAP3 (Cytosol aminopeptidase). Expected localisation Cytoplasm in most tissues; brain and muscle are exceptions (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A01921-1). Validated IHC antibody: A01921-1 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Kidney (Proximal tubules (microvilli)); negative Caudate. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human ovarian serous adenocarcinoma tissue; fixative not specified (datasheet A01921-1); 2. Fixation: Image fixative and duration unreported (datasheet A01921-1); 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 A01921-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A01921-1); 8. Primary antibody: Rabbit anti-LAP3, 2-5 μg/ml (datasheet A01921-1); 9. Primary incubation: Overnight at 4 °C (datasheet A01921-1). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Staining has medium consistency with RNA expression (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope coverage is unspecified (UniProt); Regulation: Staining regulation is unreported (UniProt). Evidence: UniProt P28838, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the cytosol. In addition localized to the calyx,…, Datasheet A01921-1, PMC5790517, PMC10882082. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/LAP3/immunohistochemistry-ihc-guide.