Anti-Serpin-A7 Rabbit Polyclonal Antibody

Frequently Asked Questions

What is the expected molecular weight for Serpin-A7 on a Western blot?

Serpin-A7 migrates at approximately 54-58 kDa on reducing SDS-PAGE, higher than the calculated mass of the 415-residue polypeptide (approximately 46 kDa) due to extensive N-linked glycosylation. The protein contains multiple glycosylation sites, and the observed molecular weight can vary depending on glycoform heterogeneity. In serum or plasma samples, you should see a single prominent band in this range. Deglycosylation with PNGase F will shift the band closer to the predicted mass and can confirm identity if you observe unexpected migration.

What sample types work best for detecting Serpin-A7 with this antibody?

Serpin-A7 is abundant in human serum and plasma, where it is synthesized by hepatocytes and secreted into circulation. For Western blot at the recommended 1:1000 dilution, dilute serum or plasma samples 1:500 to 1:2000 in loading buffer to avoid overloading. Liver tissue lysates are also suitable, as hepatocytes are the primary source. Serpin-A7 is not present at detectable levels in most extrahepatic tissues under normal conditions. For cell culture work, conditioned medium from hepatocyte lines such as HepG2 can serve as a positive control.

Does this Serpin-A7 antibody cross-react with other species beyond human?

This antibody is validated for human Serpin-A7. Cross-reactivity with mouse or rat samples is not validated and should not be assumed. Serpin-A7 shows moderate sequence conservation across mammals—human and mouse share approximately 65-70 percent amino acid identity—but epitope-level conservation determines cross-reactivity. If you are working with non-human samples, we recommend empirical testing by Western blot at 1:500 to 1:1000 dilution with appropriate positive controls such as serum. Contact us if you need guidance on predicted epitope conservation for your target species.

Can this antibody distinguish between Serpin-A7 bound and unbound to thyroid hormone?

No, this polyclonal antibody recognizes Serpin-A7 protein regardless of ligand occupancy. It detects both apo-Serpin-A7 and hormone-bound forms (T4 or T3 complexes) with equal affinity, as the epitopes recognized are unlikely to undergo conformational masking upon hormone binding. If you need to assess hormone-binding status, consider orthogonal assays such as native PAGE to separate bound and free forms, or ligand-displacement assays. For total Serpin-A7 quantification in serum or lysates—independent of functional state—this antibody is appropriate.

What dilution should I start with for IHC on formalin-fixed liver sections?

For immunohistochemistry on formalin-fixed paraffin-embedded liver tissue, start with a 1:200 to 1:500 dilution and optimize from there. Serpin-A7 is synthesized in hepatocytes, so expect cytoplasmic staining in these cells. Antigen retrieval is typically required; citrate buffer (pH 6.0) heat-induced epitope retrieval is a reasonable starting point. Include a negative control (omit primary antibody or use non-hepatic tissue such as skeletal muscle) to assess background. Because Serpin-A7 is secreted, you may also detect extracellular signal in sinusoids.

How should I store this Serpin-A7 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 can reduce titre and increase aggregation. The antibody is supplied at 100 micrograms in a stabilized buffer. After the first thaw, aliquots can be kept at 4°C for up to one month for convenience if you are running multiple experiments. Avoid prolonged exposure to room temperature. Under proper storage at -20°C, polyclonal antibodies typically retain activity for at least two years from the date of receipt. Check for precipitates before use; centrifuge briefly if cloudiness appears.

Are there known Serpin-A7 variants or isoforms I should be aware of?

Serpin-A7 is encoded by a single-copy gene on chromosome X, and the predominant form is the canonical 415-residue secreted protein. Genetic variants affecting glycosylation, stability, or T4-binding affinity have been described in patients with TBG deficiency or excess, but these do not produce distinct isoforms resolvable by standard Western blot. Post-translational modifications, especially glycosylation heterogeneity, account for the microheterogeneity seen in serum samples. This antibody targets the polypeptide backbone and should recognize common variants unless a mutation disrupts the epitope. No alternatively spliced isoforms are well-documented in the literature.

What are good positive and negative controls for validating Serpin-A7 detection?

Human serum or plasma is the best positive control, as Serpin-A7 circulates at approximately 1.5-3.0 milligrams per deciliter. HepG2 hepatocellular carcinoma cell lysate or conditioned medium is a cell-based positive control. For negative controls, use tissues or cell lines that do not express Serpin-A7, such as skeletal muscle, brain, or non-hepatic epithelial lines like HeLa or MCF-7. On Western blot, the absence of signal in these samples confirms specificity. Serpin-A7 knockout or knockdown lysates are ideal but not commercially common; serum from TBG-deficient patients is a rare research control.