Anti-Serpin-A2 Rabbit Polyclonal Antibody

Frequently Asked Questions

What molecular weight should I expect for Serpin-A2 on a Western blot?

Serpin-A2 comprises 421 amino acids with a predicted molecular weight of approximately 47 kDa. On reducing SDS-PAGE, you should observe a single band near this size. Because Serpin-A2 is a secretory protein that traffics through the endoplasmic reticulum, post-translational modifications such as glycosylation may shift the apparent molecular weight slightly higher depending on cell type and expression system. If working with recombinant protein, confirm the construct includes any signal peptide or tag that would alter the expected size. We recommend running a positive control lysate from liver or lung tissue where SERPINA2 expression has been documented.

Is Serpin-A2 expression functional in humans or is the gene a pseudogene?

This is an important nuance. While SERPINA2 has undergone pseudogenization in many human populations and shows divergent function from its paralog alpha-1-antitrypsin (SERPINA1), the gene still encodes a 421-amino-acid protein that localizes to the endoplasmic reticulum. Expression levels are low across most human tissues, which can make detection challenging. The functional role remains incompletely characterized compared to other serpins. When designing experiments, assume low endogenous expression and consider enrichment strategies or overexpression models. The protein retains structural features of serine protease inhibitors, but whether it exhibits canonical inhibitory activity requires further validation in your experimental context.

What starting dilution should I use for Western blot with this Serpin-A2 antibody?

We recommend starting at 1:1000 dilution for Western blot, which has been validated with this rabbit polyclonal antibody. Given that Serpin-A2 is expressed at low levels in most human tissues, you may need to optimize toward the higher-concentration end of the range (1:500 to 1:1000) depending on your sample abundance. Load at least 30–50 micrograms of total protein per lane and use fresh or well-preserved lysates, as serpin epitopes can degrade during freeze-thaw cycles. Titrate the antibody against your specific lysate type—hepatic or pulmonary samples typically yield better signal than other tissues based on reported expression patterns.

Can I use this antibody for immunohistochemistry on paraffin-embedded sections?

Yes, Triple Point Biologics antibodies are validated for immunohistochemistry, including paraffin-embedded tissue sections. For Serpin-A2, antigen retrieval is typically necessary; start with citrate buffer (pH 6.0) and heat-induced epitope retrieval. Because Serpin-A2 localizes to the endoplasmic reticulum and is expressed at low levels, expect primarily intracellular staining with possible secretory pathway distribution. Optimize antibody dilution starting around 1:200 to 1:500 for IHC, which is generally higher concentration than Western blot. Include appropriate negative controls (secondary antibody alone, isotype control) and positive-control tissues where SERPINA2 transcript has been confirmed by RNA-seq or similar methods.

Does this Serpin-A2 antibody cross-react with other serpin family members like SERPINA1?

While Serpin-A2 shares structural homology with alpha-1-antitrypsin (SERPINA1), this polyclonal antibody was raised against a region of Serpin-A2 intended to minimize cross-reactivity with closely related serpins. However, given the sequence similarity within the serpin superfamily, some cross-reactivity is possible, particularly if SERPINA1 is highly abundant in your sample. To confirm specificity, run parallel blots with lysates from cells overexpressing SERPINA2 versus SERPINA1, or perform peptide competition assays if critical. In tissues with high alpha-1-antitrypsin expression (liver, lung), interpret bands carefully and consider siRNA or CRISPR knockdown controls to validate that your signal corresponds to Serpin-A2.

Will this antibody work in non-human primate or mouse samples?

This antibody is validated for human samples and has potential cross-reactivity with monkey (non-human primate) based on sequence homology. Reactivity with mouse is not predicted or validated, as murine Serpina2 (which encodes a different protein involved in acute-phase response) diverges significantly from human SERPINA2. If working with cynomolgus or rhesus macaque samples, test the antibody empirically at the recommended 1:1000 dilution and include human lysate as a positive control on the same blot. For rodent studies, consider species-specific antibodies or confirm epitope conservation through alignment before investing in optimization, as serpin nomenclature and orthology are complex across species.

How should I store this Serpin-A2 antibody and what is the shelf life?

Store the antibody at –20°C in single-use aliquots to avoid repeated freeze-thaw cycles, which can reduce titer and increase aggregate formation. The 100-microgram pack size is suitable for aliquoting into 10–20 microliter volumes depending on your expected usage. Once thawed, an aliquot can be held at 4°C for up to one month if stored in the presence of carrier protein and antimicrobial preservative (check the datasheet for formulation details). Do not store diluted antibody for extended periods; prepare working dilutions fresh in blocking buffer for each experiment. With proper handling, lyophilized or glycerol-buffered polyclonal antibodies from Triple Point Biologics remain stable for at least two years from the manufacturing date.

What positive control lysate should I use to verify Serpin-A2 antibody performance?

Because endogenous Serpin-A2 expression is low in most human tissues, a strong positive control can be difficult to identify. Liver and lung tissues show detectable SERPINA2 transcript in RNA-seq datasets and are reasonable starting points for lysate screening. Alternatively, transiently transfect HEK293 or HeLa cells with a full-length SERPINA2 expression construct to generate a robust positive control with known expression. Commercial human liver lysates are available from several vendors; load 40–50 micrograms per lane and use extended ECL exposure times if necessary. Include a no-primary-antibody control and a recombinant Serpin-A2 standard if available to confirm the expected 47-kDa band and establish antibody specificity.