Anti-Serpin-B11 Rabbit Polyclonal Antibody

Frequently Asked Questions

What molecular weight should I expect for Serpin-B11 on Western blot?

Serpin-B11 (UniProt Q96P15) is a 392-amino-acid protein with a predicted molecular weight of approximately 42-43 kDa. On reducing SDS-PAGE, the band typically migrates near this range, though minor variations can occur depending on post-translational modifications or sample preparation. Because Serpin-B11 is a cytoplasmic protein lacking a signal peptide and is not glycosylated in most contexts, you should see a single, relatively sharp band. If you observe multiple bands, consider protease activity during lysis or potential splice variants, though the dominant isoform is well-characterized. Start your Western at 1:1000 dilution.

Does this Serpin-B11 antibody cross-react with other clade B serpins?

Clade B serpins share substantial sequence homology, particularly within the serpin domain scaffold, so cross-reactivity is a valid concern. This rabbit polyclonal was raised against a Serpin-B11-specific epitope region and validated on human samples. We have not observed cross-reactivity with closely related family members such as Serpin-B3, B4, or B12 in our validation panels, but we recommend including lysates from cells or tissues with known high expression of related serpins as negative or competition controls if specificity is critical to your experimental interpretation. Predicted cross-reactivity with primate orthologs is based on sequence conservation.

Which human tissues or cell lines express Serpin-B11 for positive control samples?

Serpin-B11 expression is restricted to select epithelial tissues. Ovarian carcinoma cell lines and certain prostate cancer specimens have demonstrated robust expression in published datasets, making them suitable positive controls. Normal tissue expression is relatively low and confined to stratified epithelia. If you lack access to cancer lines, consider using ovarian or prostate tissue lysates. For negative controls, hematopoietic cells or fibroblasts typically show minimal to undetectable Serpin-B11. Because the antibody targets an intracellular antigen, whole-cell lysates in RIPA or similar buffers work well. Avoid relying solely on predicted expression; empirical validation with your sample type is advisable.

What starting dilution and blocking conditions work best for Serpin-B11 Western blots?

Start at 1:1000 dilution in Tris-buffered saline with 0.1 percent Tween-20 and 5 percent non-fat dry milk or BSA. Serpin-B11 is a moderately abundant cytoplasmic protein in expressing tissues, so signal should be detectable within this range. Block membranes for one hour at room temperature. Because the antibody is a rabbit polyclonal, background can vary by lot and sample complexity; if you see high background, try increasing the dilution to 1:2000 or switching to BSA if using milk. Incubate overnight at 4°C for optimal sensitivity. Use a standard HRP-conjugated anti-rabbit secondary at the manufacturer's recommended dilution.

Can I use this antibody for immunofluorescence or IHC on human samples?

Yes. Triple Point Biologics antibodies are routinely validated for immunohistochemistry and immunofluorescence in addition to Western blot. For IHC on formalin-fixed paraffin-embedded sections, antigen retrieval is typically required; citrate buffer at pH 6.0 with heat-induced epitope retrieval is a reasonable starting point. For immunofluorescence, Serpin-B11 is cytoplasmic, so permeabilization with 0.1–0.3 percent Triton X-100 is essential. Start dilutions around 1:100 to 1:200 and titrate. Because expression is epithelial and often focal, include known positive tissue or cell controls to confirm staining specificity and avoid overinterpretation of weak signal.

Is this Serpin-B11 antibody likely to work in dog or non-human primate samples?

The antibody is validated on human samples and shows potential cross-reactivity with monkey and dog based on sequence homology in the epitope region. Primate orthologs share greater than 85 percent identity with human Serpin-B11, so cross-reactivity is predicted to be strong. Canine Serpin-B11 is less well characterized, and homology is moderate; empirical testing is recommended. If working with these species, run a dilution series starting at 1:500 and include a human positive control on the same blot to benchmark signal intensity. We have not formally validated these reactivities, so consider them preliminary until you confirm performance in your system.

How should I store the antibody and what is the expected shelf life?

Store the antibody at -20°C in single-use aliquots to avoid freeze-thaw cycles, which can reduce titer and increase aggregation. The 100 µg pack size is supplied in a glycerol-containing buffer that remains stable for at least two years at -20°C. Once thawed, an aliquot can be held at 4°C for up to one month for convenience during active experiments, but repeated freeze-thaw will degrade performance. Do not store diluted antibody in working solutions for more than one week. If you observe increased background or loss of signal over time, prepare a fresh aliquot. Sodium azide at 0.02 percent can be added as a preservative for 4°C storage.

Why does Serpin-B11 lack protease inhibitory activity despite being a serpin?

Serpin-B11 belongs to a subset of clade B serpins that have evolved away from canonical serine protease inhibition. The reactive center loop and hinge region contain structural variants that prevent the dramatic conformational change required to trap a protease in a covalent acyl-enzyme intermediate. This loss of inhibitory function is not unique; several clade B members, including Serpin-B3 and B4, are non-inhibitory. Current evidence suggests Serpin-B11 instead functions in cell death regulation, calcium handling, or stress signaling through mechanisms independent of protease inhibition. When interpreting your data, do not assume Serpin-B11 regulates proteolytic cascades directly.