Anti-Cystatin-9-Like-2 Rabbit Polyclonal Antibody

Frequently Asked Questions

What molecular weight band should I expect for Cystatin-9-Like-2 on Western blot?

The predicted translation product of CST9LP1 is 147 residues, yielding an expected molecular weight around 16-17 kDa for the full-length protein. Type 2 cystatins in this family typically migrate close to their predicted mass under reducing conditions. Because CST9LP1 is annotated as a pseudogene-derived ORF, endogenous protein expression may be low or tissue-restricted, and published literature on native protein detection remains sparse. If you observe no signal in standard lysates, consider enriching secreted fractions or testing tissues where related family members CST9 and CST9L are expressed.

What dilution should I start with for Western blot with this Cystatin-9-Like-2 antibody?

We recommend starting at 1:1000 dilution for Western blot, which has been validated with this antibody. Because Cystatin-9-Like-2 may be expressed at low levels depending on cell type or tissue, you may need to optimize between 1:500 and 1:2000 based on signal intensity and background in your specific sample. Longer exposure times or chemiluminescent substrates with extended dynamic range can help detect low-abundance targets. Always include a no-primary control to assess non-specific binding of your secondary antibody, particularly at higher primary concentrations.

Does this antibody cross-react with other cystatin family members like CST9 or CST9L?

CST9LP1 resides within the type 2 cystatin gene cluster on chromosome 20 alongside CST9, CST9L, and CST11, all of which share significant sequence homology and the conserved cystatin fold. Cross-reactivity with closely related family members is possible and has not been systematically ruled out. If specificity among paralogs is critical for your experiment, we recommend running lysates or recombinant proteins from CST9 and CST9L alongside your samples to empirically assess cross-reactivity. Peptide competition assays using the immunogen sequence can further confirm specificity.

Is Cystatin-9-Like-2 a functional protease inhibitor or just a pseudogene product?

CST9LP1 is classified as a putative pseudogene-derived open reading frame, and whether it encodes a functional cysteine protease inhibitor has not been biochemically confirmed. The predicted 147-residue product contains hallmarks of type 2 cystatins, including the QxVxG motif and cysteine residues that typically form conserved disulfide bonds. However, no substrate specificity or inhibitory activity against cathepsins or legumain has been reported. Detection of the protein in your system would be an important step toward determining if this locus produces a translated, potentially functional product.

Can I use this antibody for immunohistochemistry or immunofluorescence?

Triple Point Biologics antibodies are typically validated for Western blot and immunohistochemistry, and many perform well in immunofluorescence applications. While this specific Cystatin-9-Like-2 antibody has been validated for Western blot at 1:1000, we have not independently tested it in IHC or IF. Given the target's predicted secreted localization, antigen retrieval and permeabilization conditions will be important variables. We suggest starting with citrate-based antigen retrieval for IHC and standard methanol or Triton X-100 permeabilization for IF, then titrating antibody concentration from 1:100 to 1:500.

What sample types are best for detecting Cystatin-9-Like-2?

Because the CST9LP1 product is predicted to be secreted, conditioned media, serum, or extracellular fluid may yield better signal than whole-cell lysates, depending on expression level and secretion efficiency. If working with tissue or cells, consider fractionating cytosolic and secreted compartments. Related type 2 cystatins show tissue-restricted expression, so surveying multiple tissue types or consulting transcriptomic databases for CST9LP1 expression may guide sample selection. Positive-control lysates are not commercially available for this target; recombinant protein or overexpression constructs may be necessary to establish assay performance.

Will this antibody recognize Cystatin-9-Like-2 in mouse or rat samples?

This antibody has been validated in human samples. Cross-reactivity with mouse or rat orthologs is predicted based on sequence homology but has not been experimentally confirmed. The type 2 cystatin gene cluster shows considerable species-specific expansion and divergence, so the degree of conservation between human CST9LP1 and potential rodent orthologs may be limited. If you need to work in rodent models, we recommend empirical testing at the suggested dilution range. Running human and rodent samples side-by-side will clarify whether cross-reactivity is sufficient for your application.

How should I store the 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 aggregation. Supplementing aliquots with 50% glycerol allows storage at -20°C without freezing and can improve long-term stability. Under these conditions, rabbit polyclonal antibodies typically retain activity for at least two years. Avoid prolonged storage in frost-free freezers due to temperature cycling. Once thawed, an aliquot can be kept at 4°C with 0.02% sodium azide for short-term use, typically up to one month.