Anti-Presenilin-2 Rabbit Polyclonal Antibody

Frequently Asked Questions

What is the expected band size for Presenilin-2 on Western blot?

Full-length Presenilin-2 has a predicted molecular weight of approximately 50 kDa based on its 448-amino acid sequence. However, the mature gamma-secretase complex contains endoproteolytically cleaved fragments: an N-terminal fragment around 20 kDa and a C-terminal fragment around 25 kDa. Depending on antibody epitope and cell type, you may observe the holoprotein at 50 kDa, the processed fragments, or both. The ratio of holoprotein to fragments varies by subcellular localization and gamma-secretase assembly state. Confirm epitope mapping to predict which form your antibody recognizes.

What starting dilution should I use for Presenilin-2 Western blot?

We recommend starting at 1:1000 dilution for Western blot based on validation data with human samples. Presenilin-2 is expressed at moderate to low levels in most cell types, so enrichment of membrane fractions significantly improves signal. If working with whole-cell lysate, you may need to increase antibody concentration to 1:500 or load 30-50 micrograms total protein per lane. Always include a positive control such as HeLa or SH-SY5Y lysate. For immunofluorescence or IHC, start at 1:100 to 1:200 and optimize based on signal-to-background in your tissue context.

Does this Presenilin-2 antibody cross-react with Presenilin-1?

Presenilin-1 and Presenilin-2 share approximately 67 percent sequence identity, so cross-reactivity is a legitimate concern. This antibody is raised against human Presenilin-2 and validated specifically for PSEN2 detection. To confirm specificity in your system, we recommend running side-by-side comparisons with PSEN1 knockout or knockdown lysates if available, or blotting with a validated Presenilin-1 antibody to assess molecular weight differences. Presenilin-1 holoprotein migrates at approximately 43 kDa versus 50 kDa for Presenilin-2, which can help distinguish the two if both are expressed in your sample.

Will this antibody work in mouse or rat samples?

This antibody is validated for human Presenilin-2. Mouse and rat PSEN2 share approximately 95 percent sequence identity with human, so cross-reactivity is likely but not experimentally confirmed by us. If you plan to use mouse or rat lysates, treat this as a predicted reactivity and validate in your hands with appropriate positive controls such as brain lysate, where Presenilin-2 is endogenously expressed. Check band size and use siRNA or knockout tissue as a negative control to confirm specificity before committing to large-scale experiments.

What sample preparation method works best for detecting Presenilin-2?

Presenilin-2 is a multipass transmembrane protein localized primarily to ER and endosomal membranes, so membrane-enriched fractions yield stronger signal than whole-cell lysates. Use RIPA buffer or another detergent-containing lysis buffer with protease inhibitors; avoid gentle non-ionic detergents that may incompletely solubilize membrane complexes. Sonication or freeze-thaw cycles can improve extraction efficiency. For tissue samples, mechanical homogenization in cold lysis buffer is effective. Avoid boiling samples excessively, as aggregation of hydrophobic transmembrane domains can occur. A five-minute incubation at 70-95 degrees Celsius in sample buffer is typically sufficient.

What cell lines or tissues serve as good positive controls for Presenilin-2?

Presenilin-2 is broadly expressed but enriched in neuronal tissues and cell lines of neuronal origin. SH-SY5Y neuroblastoma cells, HeLa cells, and primary cortical neurons are reliable positive controls for Western blot. For tissue samples, brain lysate from cortex or hippocampus shows robust expression. If studying disease models, note that PSEN2 mutations are associated with familial Alzheimer disease, so mutant cell lines may exhibit altered processing or stability. Always include a no-primary-antibody control or PSEN2 knockdown lysate to confirm band identity and rule out nonspecific binding.

How should I store this Presenilin-2 antibody and what is the shelf life?

Store the antibody at minus 20 degrees Celsius in single-use aliquots to avoid repeated freeze-thaw cycles, which can reduce titer and increase aggregation. The 100-microgram pack size allows you to prepare multiple working aliquots. If you use the antibody frequently, a working aliquot can be kept at 4 degrees Celsius for up to one month; add sodium azide at 0.02 to 0.05 percent as a preservative if storing liquid at 4 degrees long-term. Avoid storing diluted antibody. Shelf life is typically two years from date of manufacture when stored properly at minus 20 degrees.

Why do I see multiple bands when probing for Presenilin-2 on Western blot?

Multiple bands are common and often reflect the biology of Presenilin-2. The holoprotein at approximately 50 kDa undergoes endoproteolytic cleavage to generate N-terminal and C-terminal fragments around 20 and 25 kDa, both of which are functional components of the gamma-secretase complex. You may also observe higher molecular weight bands representing incompletely denatured oligomers or gamma-secretase subcomplexes, particularly if samples are not fully reduced or boiled. Post-translational modifications such as phosphorylation can cause minor shifts. Use a validated positive control lysate to distinguish biological processing from nonspecific binding or degradation.