Anti-Marapsin-2 Rabbit Polyclonal Antibody

Frequently Asked Questions

What molecular weight band should I expect for Marapsin-2 on Western blot?

Marapsin-2 (PRSS38) has a predicted molecular weight of approximately 36 kDa based on its 326 amino acid sequence. On Western blot, you should observe a band near this size, though the exact migration may vary slightly depending on post-translational modifications or proteolytic processing. Because Marapsin-2 is a secreted serine protease, confirm that your sample type contains the secreted form; testicular or epididymal lysates and seminal plasma are appropriate sources. If you see multiple bands, consider that activation cleavage or glycosylation may alter apparent molecular weight. Always include a molecular weight ladder and positive control tissue.

Which tissues or cell types express Marapsin-2 for use as positive controls?

Marapsin-2 expression is largely restricted to reproductive tissues. Human and mouse testis, epididymis, and sperm preparations serve as reliable positive control samples. For validation, testicular lysates provide robust signal due to the concentration of developing and mature germ cells. Seminal plasma can also be used if you are studying the secreted protease in physiological context. Non-reproductive tissues generally do not express detectable PRSS38, making them suitable negative controls. When optimizing your assay, prepare lysates from adult reproductive tissues; expression may be low or absent in immature or non-spermatogenic samples.

What starting dilution should I use for Western blot with this Marapsin-2 antibody?

We recommend starting at 1:1000 dilution for Western blot applications, which has been validated for this rabbit polyclonal antibody. This dilution typically provides good signal-to-noise ratio with testicular or sperm lysates containing 20-50 micrograms total protein per lane. If your initial signal is weak, you can increase antibody concentration to 1:500, or conversely dilute to 1:2000 if background is high. Incubate overnight at 4°C for optimal binding. Because Marapsin-2 is a relatively low-abundance secreted protease, ensure your sample preparation captures the relevant subcellular fraction and that protein loading is adequate for detection.

Is this antibody validated for mouse and rat, or only predicted cross-reactivity?

This antibody is validated for human Marapsin-2 detection. Cross-reactivity with mouse and rat is predicted based on sequence homology in the antigenic region but has not been experimentally confirmed by Triple Point Biologics. If you are working with rodent samples, we suggest treating the antibody as experimental for those species. Run positive controls with human tissue alongside your mouse or rat lysates, and be prepared to optimize dilution and blocking conditions. Primate, canine, and other mammalian orthologs are also predicted to cross-react, but validation in your specific model system is advisable before committing to large-scale experiments.

Can I use this antibody for immunofluorescence or IHC on sperm or testis sections?

Yes, Triple Point Biologics antibodies are validated for Western blot; immunohistochemistry and immunofluorescence validation is in progress. For Marapsin-2 localization in testis sections, standard antigen retrieval with citrate buffer (pH 6.0) is a reasonable starting point, followed by blocking and overnight incubation with primary antibody at 1:100 to 1:200 dilution. For sperm immunofluorescence, fix cells with methanol or paraformaldehyde, permeabilize if needed, and use similar dilutions. Because Marapsin-2 is secreted, expect extracellular or plasma membrane-associated signal in mature sperm. Include secondary-only controls to assess nonspecific binding, especially with reproductive tissues that can show high background.

How should I prepare sperm lysates to preserve Marapsin-2 for Western blot?

Marapsin-2 is a serine protease, so include protease inhibitors in your lysis buffer to prevent autoproteolysis and degradation by other sperm proteases. Use a cocktail containing serine protease inhibitors such as PMSF or aprotinin immediately upon sample collection. Lyse purified sperm in RIPA or similar buffer on ice, and process samples quickly. If studying the secreted form, consider separating the seminal plasma fraction by centrifugation before cell lysis. Snap-freeze aliquots in liquid nitrogen and store at -80°C to preserve protease integrity. Avoid repeated freeze-thaw cycles, which can degrade both antigen and enzymatic activity.

What is known about Marapsin-2 isoforms or splice variants that might affect detection?

Currently, the primary characterized form of Marapsin-2 is the full-length 326 amino acid protein encoded by PRSS38. There is limited published information on alternative splice variants or tissue-specific isoforms. If you detect multiple bands on Western blot, consider proteolytic activation or processing rather than splice variants, as serine proteases are often synthesized as zymogens and cleaved to active forms. The catalytic domain structure is conserved, so this polyclonal antibody should recognize both proenzyme and processed forms if the epitope region remains intact. If you observe unexpected banding patterns, verify sample integrity and consider running non-reducing gels to assess disulfide-linked complexes.

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

Store the antibody at -20°C upon receipt. The 100 microgram pack size is supplied as a liquid or lyophilized format; consult the product datasheet for your specific lot. For liquid antibodies, aliquot into single-use volumes to avoid repeated freeze-thaw cycles, which can reduce binding activity over time. Lyophilized antibodies should be reconstituted per instructions and then aliquoted. Under proper storage at -20°C without repeated thawing, rabbit polyclonal antibodies typically remain stable for at least one year, often longer. For long-term storage beyond two years, keep at -80°C. Avoid storing in frost-free freezers, which cycle temperatures and can degrade protein reagents.