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FKBP5 / Peptidyl-prolyl cis-trans isomerase FKBP5 · IHC design guide
Design Immunohistochemistry for FKBP5
Plan chromogenic paraffin IHC for FKBP5 using the catalog antibody at 1:50 (datasheet M04182). Select controls and score nuclear staining alongside weaker cytoplasmic signal (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FKBP5 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 | Nuclear and cytoplasmic; tissue staining favors nuclei (HPA tissue IHC) | |
| Staining pattern | General nuclear staining with weaker cytoplasmic signal (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet M04182) | |
| Positive control | Adipose tissue+4 more · see all | |
| Negative control | None in HPA (detected in all 45 tissues); use no-primary + isotype controls |
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 | Broad cell-type expression can complicate cell-specific scoring (HPA tissue IHC) | |
| Regulation | RNA is tissue-enhanced in muscle and tongue (HPA tissue RNA) | |
| Isoform / epitope | 2 isoforms; epitope differences are unspecified (UniProt) |
Section 1
Recommended FKBP5 IHC & IF Protocols
The catalog antibody protocol uses EDTA pH 8.0 retrieval (datasheet). The published IHC protocols below report conditions for rat prefrontal cortex, ocular tissue, and human thyroid tissue (PMC12893177; PMC9457885; PMC8108082).
| Sample | Paraffin-embedded human colorectal adenocarcinoma tissue; fixative not specified (datasheet M04182) |
| Fixation | Image fixative and duration unreported (datasheet M04182); 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 M04182); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet M04182) |
| Primary antibody | Rabbit monoclonal (clone AFBE-6) anti-FKBP5, 1:50 (datasheet M04182) |
| Primary incubation | Overnight at 4 °C (datasheet M04182) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet M04182) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FKBP5-positive staining in adipocytes of adipose tissue (HPA tissue IHC: High). HPA tissue profile: General nuclear expression combined with lower cytoplasmic expression. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval for the catalog antibody (datasheet: M04182); these published excerpts do not specify a retrieval condition (PMC12893177; PMC9457885; PMC8108082).
Section 2
What Is the Expected FKBP5 Staining Pattern?
FKBP5 is a cytoplasmic and nuclear protein with no transmembrane segment (UniProt Q13451). In tissue sections, expect predominantly nuclear staining with weaker cytoplasmic staining (HPA: tissue IHC profile). High staining is documented in adipocytes, adrenal glandular cells, bone marrow hematopoietic cells, and several other listed cell populations (HPA: tissue IHC). HPA rates the overall tissue staining profile Enhanced, citing consistency with RNA expression (HPA: tissue IHC reliability).
| Nuclei stain more strongly than cytoplasm in a documented positive cell population. | This matches HPA's general nuclear expression with lower cytoplasmic expression (HPA: tissue IHC profile). Compare cells of the same type and score nuclear and cytoplasmic staining separately (general IHC practice); HPA's profile does not require identical intensity in every tissue. |
| Staining is confined to cell borders or extracellular material, with little intracellular signal. | That distribution conflicts with the reported nuclear and cytoplasmic locations and the absence of a transmembrane segment (UniProt Q13451; HPA: tissue IHC profile). Treat it as suspect and check morphology and controls before assigning it to FKBP5 (general IHC practice). |
| An unexpected cell population stains while the documented positive cells in the same section do not. | Cross-reactivity or endogenous detection activity is possible (general IHC practice). HPA's high-staining list identifies useful reference populations; it is not an exhaustive list of cells capable of expressing FKBP5 (HPA: tissue IHC). |
| Color spreads across nuclei, cytoplasm, and surrounding tissue without clear cell boundaries. | Diffuse background makes compartment and cell-type scoring unreliable (general IHC practice). Compare with a no-primary control and inspect the counterstain and tissue morphology before interpreting the color as FKBP5 signal (general IHC practice). |
| There is no signal in a section containing an expected positive population. | Absent staining in adipocytes or adrenal glandular cells, for example, needs a technical check because both are listed as High (HPA: tissue IHC). It does not establish biological absence until tissue preservation, detection controls, and the antibody's validated IHC conditions have been reviewed (general IHC practice). |
💡Expected FKBP5 appearanceCall a result positive when identifiable cells show predominantly nuclear staining with weaker cytoplasmic staining, particularly in an HPA High population; isolated membrane-like or extracellular color is suspect (HPA: tissue IHC profile and High cell populations; UniProt Q13451 topology).
| Compartment and cell identity | HPA describes general nuclear staining with lower cytoplasmic staining, while UniProt lists both nucleus and cytoplasm (HPA: tissue IHC profile; UniProt Q13451). Interpret intensity within morphologically identifiable cells; a positive color alone cannot establish the reported distribution (general IHC practice). |
| Choice of reference tissue | HPA lists High staining in adipocytes, adrenal glandular cells, appendix glandular cells, bone marrow hematopoietic cells, bronchial respiratory epithelial cells, cerebellar granular cell nuclei, cervical glandular cells, and colon endothelial cells (HPA: tissue IHC). These are documented examples, not a ranked sensitivity panel or a list of negative tissues. |
| Antibody validation | HPA marks HPA031092 and CAB009315 Enhanced for IHC, and HPA031093 and HPA031095 Supported for IHC (HPA: antibody validation). Those grades apply to the named antibodies; they do not establish equivalent performance for another catalog antibody or define its working dilution. |
| Protein forms and epitope limits | UniProt records two isoforms, no signal peptide or propeptide, and a single annotated chain spanning residues 1–457 (UniProt Q13451). The supplied records do not locate this guide's antibody epitope or establish isoform-specific staining; avoid interpreting differences between sections as isoform changes. |
| Situation | Likely cause | Next action |
|---|---|---|
| Strong signal appears mainly at cell borders or outside cells. | The distribution differs from the reported intracellular locations (UniProt Q13451; HPA: tissue IHC profile). | Review cell morphology, inspect a no-primary control, and verify the antibody's IHC validation before scoring the signal (general IHC practice). |
| Cells outside the expected population stain more strongly than nearby documented positive cells. | Cross-reactivity or endogenous chromogenic detection activity may contribute (general IHC practice); HPA's High list is not exclusive (HPA: tissue IHC). | Compare the suspect cells with the relevant HPA reference population and detection controls; score cell types separately (HPA: tissue IHC; general IHC practice). |
| The entire section has diffuse brown background. | Nonspecific binding or endogenous detection activity can obscure compartment boundaries (general IHC practice). | Check no-primary and detection controls, then review blocking, washes, and chromogen development under the detection system's instructions (general IHC practice). |
| A documented High population has no detectable staining. | The assay may have failed, or the sampled section may lack well-preserved identifiable target cells (HPA: High cell populations; general IHC practice). | Confirm the target cells on the counterstain and check antibody dilution, antigen retrieval, and detection against the antibody's IHC-P instructions (general IHC practice); FKBP5-specific fixation sensitivity is unreported in the supplied sources. |
| Nuclear intensity varies across otherwise comparable cells. | HPA reports a general pattern, not a required intensity for every cell or section (HPA: tissue IHC profile). Uneven background can also affect scoring (general IHC practice). | Score nuclei and cytoplasm separately in identifiable cells, and compare sections only after checking controls and background (general IHC practice). |
| Does IF/ICC show the same compartment pattern? | HPA reports mainly nucleoplasmic FKBP5, with additional nucleolar fibrillar center and cytosolic localization in ICC-IF (HPA: subcellular profile). | Use that localization to interpret IF/ICC images; consult the separate IF/ICC guide for that application's procedure (HPA: subcellular profile). |
Experiment evidence
IHC & IF images showing FKBP5 staining
M04182 · IHCIHC analysis of FKBP5 using anti-FKBP5 antibody (M04182). FKBP5 was detected in a paraffin-embedded section of human colorectal adenocarcino
M04182 · IHCIHC analysis of FKBP5 using anti-FKBP5 antibody (M04182). FKBP5 was detected in a paraffin-embedded section of human liver cancer tissue. He
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000096060-FKBP5/tissue/cerebral+cortex#imid_8030039
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000096060-FKBP5/tissue/colon#imid_8027461
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000096060-FKBP5/tissue/liver#imid_8027462
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000096060-FKBP5/tissue/kidney#imid_8027455
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA031092; green = FKBP5, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA031092; green = FKBP5, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FKBP5 IHC & IF
🧪Run bone marrow first; hematopoietic cells should stain (HPA: High in bone marrow hematopoietic cells). HPA detects FKBP5 in all 45 scored tissues, so use no-primary and isotype controls instead of a negative tissue (HPA: no negative rows); cells without specific signal on the positive slide, if present, should show only counterstain and background, but are not established biological negatives (standard IHC practice).
Positive control tissue: Adipose tissue (Adipocytes, HPA High)
Negative control tissue: None in HPA: FKBP5 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show FKBP5 in A-431, U-251MG, U2OS, HEK293, ASC52telo, NIH 3T3, with annotated localisation: Nucleoplasm (approved) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only control and a concentration-matched rabbit IgG isotype control for the rabbit catalog antibody, plus FKBP5 knockout material or a validated immunizing-peptide block as a biological specificity control (caption: rabbit anti-FKBP5; standard IHC practice). Quench endogenous peroxidase and assess granular background in bone marrow hematopoietic cells before interpreting DAB staining (HPA: bone marrow hematopoietic cells; standard IHC practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported in the supplied evidence; the selected M04182 paraffin-section caption does not state a fixative (M04182 caption: fixative unreported). Heat retrieval in EDTA at pH 8.0 was used in that IHC example, but retrieval dependence is unreported (M04182 caption). Frozen sections and IF have no documented ease advantage here; in bone marrow, endogenous peroxidase in myeloid cells can complicate chromogenic scoring (standard IHC practice).
HPA tissue IHC evidence for FKBP5
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.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | High | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | High | Protein (IHC) | HPA → |
| Appendix | Glandular cells | High | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: FKBP5 is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced FKBP5 IHC Tips
Troubleshoot FKBP5 staining in paraffin sections by checking retrieval, compartment, tissue context, controls, and scoring before interpreting signal.
What retrieval should I try first when FKBP5 staining is weak?
Start with heat-mediated retrieval in EDTA at pH 8.0 for paraffin sections (datasheet M04182). The selected image used that retrieval before overnight incubation at 4°C with antibody at 1:50, so reproduce those conditions when comparing your result (caption M04182). If signal remains weak, compare a second retrieval condition on adjacent sections while keeping antibody concentration, heating time, and detection constant (standard IHC practice). Inspect tissue structure and background alongside signal, since harsher heating can compromise morphology and make an apparent gain difficult to interpret (standard IHC practice).
How should I troubleshoot fixation-dependent loss of FKBP5 staining?
The selected paraffin-section caption does not state a fixative, so FKBP5 sensitivity to a particular fixative or fixation duration is unknown for this antibody (caption M04182). Record fixation method and duration for each specimen, then compare sections processed with the same retrieval and detection conditions (standard IHC practice). Include a concurrently processed positive-control section to help distinguish a specimen-level problem from a staining-run problem (standard IHC practice; HPA: high staining in adipocytes). If staining differs across specimens, report the processing difference without assigning it to a particular FKBP5 epitope unless that effect is directly tested (standard IHC practice).
How should I assess nuclear versus cytoplasmic FKBP5 staining?
Score nuclear and cytoplasmic staining separately because FKBP5 is reported in both compartments, while tissue IHC shows general nuclear expression with lower cytoplasmic expression (UniProt Q13451 subcellular; HPA tissue IHC profile). Use a nuclear counterstain to define cell boundaries and assess whether cytoplasmic color belongs to the same cells (standard IHC practice). Predominantly nuclear signal can fit the reported pattern, but the balance may differ between cells and specimens (HPA tissue IHC profile; standard IHC interpretation). Compare compartment patterns with a control section and inspect diffuse color outside cells before calling unusually strong cytoplasmic staining specific (standard IHC practice).
Can this stain distinguish FKBP5 isoforms or modified epitopes?
Do not assign isoform identity from staining alone: FKBP5 has 2 reported isoforms, and the supplied antibody information does not map its epitope (UniProt Q13451 isoforms; caption M04182). The protein has FKBP-type PPIase domains at residues 42–130 and 157–243, but domain annotation does not establish which sequence this antibody recognizes (UniProt Q13451 domains; caption M04182). Report staining as FKBP5 immunoreactivity unless isoform-specific recognition is independently established (standard IHC interpretation). Document retrieval and processing conditions when comparing specimens, since the record also lists acetylated and phosphorylated residues without establishing their effect on this antibody (UniProt Q13451 modified residues; standard IHC practice).
How can I check FKBP5 localization by multiplex IF?
For a separate IF experiment, pair FKBP5 with an endothelial marker when examining colon, where endothelial cells show high tissue-IHC staining (HPA: colon endothelial cells high; standard IF practice). Choose spectrally separated fluorophores and favor a longer-wavelength channel for the weaker signal if tissue autofluorescence interferes (standard IF practice). FKBP5 has no transmembrane segment and is reported in the nucleus and cytoplasm, so use permeabilisation suitable for intracellular epitopes and verify its effect on the companion marker (UniProt Q13451 topology and subcellular; standard IF practice). Check single-color controls before interpreting overlap, and establish IF performance independently because the selected antibody evidence describes chromogenic paraffin-section IHC (caption M04182; standard IF practice).
What should I check when DAB background obscures FKBP5?
The selected chromogenic example used 10% goat serum blocking, antibody at 1:50 overnight at 4°C, and peroxidase-based DAB development (caption M04182). First inspect a section processed without primary antibody to separate detection-system color from antibody-dependent staining (standard IHC practice). Review peroxidase blocking, wash stringency, and development time on matched sections; these are general chromogenic workflow variables rather than FKBP5-specific findings (standard IHC practice). If background persists, titrate the primary antibody around the documented condition and compare signal within intact cells against extracellular deposits or tissue edges (caption M04182; standard IHC practice).
How should I quantify FKBP5 across paraffin sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and compartment before scoring, because tissue IHC reports general nuclear expression with lower cytoplasmic expression and high staining in several distinct cell types (HPA tissue IHC profile). For a defined region, record the percentage of positive cells and a compartment-specific intensity score; an H-score can summarize intensity-weighted positivity (standard IHC practice). Normalize counts to the number of eligible cells, or report positive-cell density per mm² of viable tissue when cell counting is impractical (standard IHC quantification practice). Apply identical thresholds and sampling rules across sections, and exclude folds, damaged edges, and necrotic regions from the measured area (standard IHC practice).
When is an apparent FKBP5-positive area likely artefactual?
A plausible signal should lie within cells and be assessed against FKBP5's reported nuclear and cytoplasmic distribution (UniProt Q13451 subcellular; HPA tissue IHC profile). Interpret cell identity in context: high tissue-IHC staining is reported for colon endothelial cells and adipocytes, so a positive area need not represent every neighboring cell (HPA: colon endothelial cells high; HPA: adipocytes high). Treat staining concentrated at cut edges, folds, or necrotic regions as suspect until matched intact tissue shows the same pattern (standard IHC practice). Use a no-primary control to check endogenous enzyme or detection-related color, then confirm that any claimed FKBP5 signal exceeds that control (standard IHC practice).
Boster reagents
Best FKBP5 / Peptidyl-prolyl cis-trans isomerase FKBP5 IHC Antibodies
Catalog antibodies cover human and rat IHC, with paraffin-section images for M04182 (catalog image captions); M04182 also lists IF/ICC, but no IF image is supplied (catalog applications and image records).
Real IHC data
Anti-FKBP51 Monoclonal Antibody
Cat # M04182
M04182 has IHC images from paraffin sections of human colorectal adenocarcinoma, human liver cancer, and rat liver (M04182 image captions); it also lists IF/ICC for human and rat (catalog applications and reactivity). A04182-2 lists IHC and human, mouse, and rat reactivity, but supplies no IHC or IF image (catalog applications, reactivity, and image records).
Which to pick: Choose M04182 for paraffin-section IHC when its imaged human or rat samples fit your study (M04182 image captions); its rabbit monoclonal clone is AFBE-6 (catalog clone). For IF/ICC, M04182 lists those applications at 1:50, although no IF image is supplied (catalog applications, dilution, and image records). For mouse reactivity, consider rabbit polyclonal A04182-2, which lists mouse and IHC without an accompanying IHC image (catalog reactivity, application, and image records); M04182’s captions describe paraffin sections but do not report the fixative (M04182 image captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q13451 (FKBP5_HUMAN, Peptidyl-prolyl cis-trans isomerase FKBP5).
- Human Protein Atlas. FKBP5 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. FKBP5 subcellular location (ICC-IF): Mainly localized to the nucleoplasm. In addition localized to the nucleoli fibrillar center and cytosol..
- Human Protein Atlas. FKBP5 antibody validation summary (4 antibodies).
- Chronic adolescent stress alters GR-FKBP5 interactions in the hippocampus of adult female rats. Stress (Amsterdam, Netherlands) 2024 — PMC11067065.
- Immune-related biomarkers for major depressive disorder identified via integrated bioinformatics and machine learning. European journal of psychotraumatology 2026 — PMC12893177.
- Dexamethasone Intravitreal Implant Is Active at the Molecular Level Eight Weeks after Implantation in Experimental Central Retinal Vein Occlusion. Molecules (Basel, Switzerland) 2022 — PMC9457885.
- FK506-binding protein 5 promotes the progression of papillary thyroid carcinoma. The Journal of international medical research 2021 — PMC8108082.
- PubMed PMID:9125197 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:14574404 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FKBP5 (Peptidyl-prolyl cis-trans isomerase FKBP5). Expected localisation Nuclear and cytoplasmic; tissue staining favors nuclei (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet M04182). Validated IHC antibody: M04182 at 1:50 (the product's own IHC validation image is shown). Controls (HPA): positive Adipose tissue (Adipocytes); negative None in HPA (detected in all 45 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human colorectal adenocarcinoma tissue; fixative not specified (datasheet M04182); 2. Fixation: Image fixative and duration unreported (datasheet M04182); 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 M04182); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet M04182); 8. Primary antibody: Rabbit monoclonal (clone AFBE-6) anti-FKBP5, 1:50 (datasheet M04182); 9. Primary incubation: Overnight at 4 °C (datasheet M04182). Watch for: Fixation: Keep fixation conditions consistent across sections. (standard IHC practice; not target-specific); Caveat: Broad cell-type expression can complicate cell-specific scoring (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope differences are unspecified (UniProt); Regulation: RNA is tissue-enhanced in muscle and tongue (HPA tissue RNA). Evidence: UniProt Q13451, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the nucleoplasm. In addition localized to the…, Datasheet M04182, PMC12893177, PMC9457885. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FKBP5/immunohistochemistry-ihc-guide.