Anti-Serpin-B13 Rabbit Polyclonal Antibody

Frequently Asked Questions

What molecular weight band should I expect for Serpin-B13 on Western blot?

Serpin-B13 migrates at approximately 45-47 kDa on Western blot, which corresponds to the predicted molecular weight of the 391-amino acid protein. Because Serpin-B13 is an intracellular clade B serpin lacking a signal peptide, you should not observe higher molecular weight glycosylated forms. If you see multiple bands, consider post-translational modifications or proteolytic cleavage, though these are not widely reported for Serpin-B13. Use keratinocyte lysates such as HaCaT cells as a positive control, where Serpin-B13 is endogenously expressed.

What is the recommended starting dilution for Serpin-B13 antibody in Western blot?

Start at 1:1000 dilution in blocking buffer for Western blot, as validated with this antibody. Depending on expression levels in your sample and signal strength, you may need to optimize between 1:500 and 1:2000. Serpin-B13 expression is relatively low in most tissues, so keratinocyte or epidermal lysates will give stronger signal than fibroblasts or non-epithelial cells. Load 20-40 micrograms total protein per lane and use overnight incubation at 4°C if signal is weak at the recommended dilution.

Is Serpin-B13 expressed in normal human skin and which cell types should I use as positive controls?

Serpin-B13 is expressed in normal human epidermis, particularly in differentiating keratinocytes. HaCaT keratinocytes are the standard positive control, as this immortalized human keratinocyte line was used in the original identification of Serpin-B13 as a UV-repressible gene. Primary human keratinocytes and epidermal tissue lysates also express Serpin-B13. Expression is cytoplasmic and may be modulated by differentiation status, UV exposure, and inflammatory signals. Fibroblasts and non-epithelial cell lines typically show low or absent expression, making them suitable negative controls.

Does this Serpin-B13 antibody cross-react with mouse or rat samples?

This antibody is validated for human Serpin-B13 and cross-reactivity with monkey is predicted based on sequence homology. Cross-reactivity with mouse or rat has not been validated. Human and mouse Serpin-B13 share moderate sequence identity, so cross-reactivity is possible but should be confirmed experimentally in your hands. If working with rodent samples, include a species-specific positive control and consider peptide competition assays to confirm specificity. Pan-reactivity claims require empirical validation; we do not make unsupported cross-species guarantees.

Can I use this antibody for immunohistochemistry or immunofluorescence on skin sections?

This rabbit polyclonal is suitable for immunohistochemistry and immunofluorescence, methods routinely validated across our antibody line. For IHC on paraffin-embedded skin sections, use heat-mediated antigen retrieval with citrate buffer, pH 6.0. Start with 1:100 to 1:200 dilution and optimize based on background. Because Serpin-B13 is cytoplasmic, expect diffuse cytoplasmic staining in keratinocytes. For IF on cultured keratinocytes, fix with 4 percent paraformaldehyde, permeabilize with 0.1 percent Triton X-100, and begin at 1:50 to 1:100 dilution.

What sample preparation considerations are important for detecting Serpin-B13 in cell lysates?

Because Serpin-B13 is a cytoplasmic serine protease inhibitor, standard RIPA or NP-40 lysis buffers with protease inhibitor cocktail are appropriate. Avoid excessive boiling, which can aggregate serpins; heat samples at 95°C for 5 minutes maximum. Serpin-B13 expression may be low in non-keratinocyte samples, so use sufficient protein input (30-50 micrograms per lane). If studying UV or inflammatory regulation, harvest cells at defined time points post-treatment, as Serpin-B13 is UV-repressible and may fluctuate with differentiation state.

How should I store the Serpin-B13 antibody and what is the expected shelf life?

Store the antibody at -20°C in single-use aliquots to avoid repeated freeze-thaw cycles, which degrade antibody activity over time. The 100-microgram pack size is sufficient for multiple experiments when aliquoted upon receipt. Once thawed, an aliquot can be stored at 4°C with 0.02 percent sodium azide for up to one month. Do not store diluted antibody in blocking buffer for more than one week. Properly stored aliquots remain stable for at least one year from receipt. Centrifuge briefly before use if precipitate forms after thawing.

Are there known isoforms or splice variants of Serpin-B13 I should be aware of?

Serpin-B13 is primarily expressed as a single 391-amino acid isoform encoded by the SERPINB13 gene on chromosome 18. Alternative splice variants have not been extensively characterized in the literature, and the UniProt entry Q9UIV8 lists the canonical sequence. This antibody is raised against a broad epitope region, so it should detect the full-length protein. If you observe multiple bands on Western blot, consider proteolytic cleavage or cross-reactivity rather than splice variants. The serpin family is large, so include peptide competition controls if specificity is critical.