Anti-Serpin-A6 Rabbit Polyclonal Antibody

Frequently Asked Questions

What is the expected molecular weight of Serpin-A6 on Western blot?

Serpin-A6 migrates at approximately 52–58 kDa on reducing SDS-PAGE, slightly higher than the 45 kDa calculated from the 405-amino-acid sequence due to N-linked glycosylation. The protein contains two glycosylation sites, and the extent of modification varies by tissue and species. In human plasma samples, you may observe a diffuse band or doublet reflecting glycoform heterogeneity. Deglycosylation with PNGase F shifts the band to around 45 kDa, confirming identity. Mouse and rat Serpin-A6 orthologs show similar migration patterns.

What dilution should I start with for Western blot with this Serpin-A6 antibody?

We recommend starting at 1:1000 in blocking buffer for overnight incubation at 4°C or 1–2 hours at room temperature. Serpin-A6 is abundant in liver lysates and plasma, so signal saturation is common; you may need to dilute further to 1:2000 or 1:5000 depending on sample load. For cell-line lysates with lower expression, 1:500 to 1:1000 typically provides adequate signal. Titre the antibody against your specific lysate and detection system to optimize signal-to-noise before scaling up experiments.

Does this antibody detect mouse and rat Serpin-A6 or only human?

The antibody is validated for human Serpin-A6. Mouse and rat cross-reactivity are predicted based on sequence homology in the immunogen region but have not been experimentally confirmed. Human and mouse Serpin-A6 share approximately 65–70 percent amino-acid identity overall, with higher conservation in structured domains. If you plan to work with rodent samples, we recommend testing the antibody alongside a positive control such as mouse liver lysate or recombinant mouse Serpin-A6, and verifying the expected band at 52–58 kDa before committing to large-scale experiments.

What tissues or cell lines are good positive controls for Serpin-A6 expression?

Serpin-A6 is synthesized predominantly in hepatocytes, so liver lysate or homogenate is the strongest positive control. Human plasma or serum diluted in sample buffer also works well, though high abundance may require minimal loading to avoid saturation. For cell lines, HepG2 hepatoma cells express detectable Serpin-A6, albeit at lower levels than primary hepatocytes. HepaRG differentiated cells are another option. Negative controls include non-hepatic tissues with minimal expression such as skeletal muscle or brain lysate, though low-level ectopic expression has been reported in some contexts.

Does Serpin-A6 function as a protease inhibitor or just a carrier protein?

Unlike most serpins, Serpin-A6 functions primarily as a high-affinity steroid carrier rather than a protease inhibitor. It binds and transports cortisol and progesterone in circulation, buffering free hormone concentrations. The protein retains the serpin fold but lacks the reactive-center loop conformation required for efficient protease inhibition. However, Serpin-A6 is cleaved by neutrophil elastase at sites of inflammation, releasing bound cortisol locally. This cleavage inactivates the carrier function and may modulate local glucocorticoid activity. Most experimental studies focus on its hormone-transport role rather than any inhibitory activity.

Can I use this antibody for immunohistochemistry on paraffin sections?

Triple Point Biologics antibodies are validated for Western blot applications. For paraffin-embedded tissue, antigen retrieval is typically necessary. Citrate buffer (pH 6.0) heat-induced epitope retrieval is a standard starting point for serpin family members, though Tris-EDTA (pH 9.0) may also work depending on fixation. Dilutions of 1:100 to 1:500 are typical for IHC. Serpin-A6 staining should localize to hepatocyte cytoplasm in liver sections. Test your tissue and fixation protocol with known positive controls before adapting the method to experimental samples.

How should I store this Serpin-A6 antibody and what is the shelf life?

Store the antibody at –20°C in small aliquots to avoid repeated freeze-thaw cycles, which can reduce titer and increase aggregation. The product ships as 100 µg in a buffered solution; upon receipt, divide into single-use volumes if you plan infrequent experiments. Stability is typically two years from manufacture when stored frozen and not thawed more than three times. For frequent use, a working aliquot can be held at 4°C for one month with sodium azide preservative. Check the product datasheet for lot-specific storage buffer composition and expiration date.

What is the difference between cleaved and intact Serpin-A6 on Western blot?

Intact Serpin-A6 migrates at 52–58 kDa. Cleavage by neutrophil elastase generates fragments of approximately 42 kDa and smaller peptides, depending on the cleavage site. Elastase cuts within the reactive-center loop region, releasing bound steroid and abolishing carrier function. If you are studying inflammatory samples, sepsis models, or neutrophil-rich tissues, you may observe both full-length and cleaved bands. The appearance of lower-molecular-weight fragments can serve as a readout of local elastase activity. Epitope location matters: antibodies targeting the N-terminus will detect both forms, whereas C-terminal antibodies may miss cleaved products.