Anti-Calpain-6 Rabbit Polyclonal Antibody

Frequently Asked Questions

What molecular weight band should I expect for Calpain-6 on Western blot?

Calpain-6 (CAPN6) runs at approximately 70-75 kDa on Western blot, corresponding to its 641-amino acid sequence. You may observe slight mobility shifts depending on post-translational modifications or gel conditions. Unlike classical calpains that show autocatalytic processing fragments, Calpain-6 lacks proteolytic activity and typically appears as a single predominant band. If you observe multiple bands, consider whether your sample preparation conditions preserve the full-length protein or whether you're detecting splice variants. Using fresh lysates with protease inhibitors helps minimize non-specific degradation.

Does Calpain-6 have catalytic activity I should account for in my experiments?

No. Calpain-6 is an atypical, catalytically inactive member of the calpain family due to substitutions in the conserved catalytic triad residues within its protease domain. This distinguishes it from classical calpains like CAPN1 and CAPN2. Instead of proteolytic function, Calpain-6 acts as a microtubule-stabilizing protein and modulates RAC1 signaling through protein-protein interactions with ARHGEF2. When designing experiments, focus on its scaffolding and regulatory roles in cytoskeletal dynamics rather than expecting substrate cleavage. This also means you won't need protease activity assays to assess Calpain-6 function.

What dilution should I start with for Western blot with this Calpain-6 antibody?

Start with 1:1000 dilution in your blocking buffer for Western blot applications. This is the validated dilution for detecting endogenous Calpain-6 in whole cell lysates. Depending on expression levels in your specific cell type or tissue, you may need to optimize between 1:500 and 1:2000. Calpain-6 expression is relatively low in many cell types and concentrates in perinuclear cytoplasm, so using 20-30 µg total protein per lane and longer exposure times (ECL incubation 3-5 minutes) often improves detection. Include a positive control lysate from a cell line with known Calpain-6 expression.

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

This antibody is validated in human samples. Cross-reactivity with mouse and rat is predicted based on sequence homology but not experimentally validated by Triple Point Biologics. Human CAPN6 shares approximately 85-90% amino acid identity with mouse and rat orthologs in the immunogenic regions, suggesting the antibody should recognize these species. However, you should confirm specificity in your system using appropriate controls such as CAPN6 knockout lysates or siRNA knockdown samples if working with rodent models. Titrate the antibody starting at 1:1000 and verify the expected 70-75 kDa band.

What subcellular localization should I expect when using this antibody for immunofluorescence?

Calpain-6 localizes primarily to the perinuclear cytoplasm and associates with microtubules. In immunofluorescence experiments, expect punctate or diffuse cytoplasmic staining concentrated around the nuclear envelope, often with fibrillar patterns along microtubule networks in spread cells. During cell migration, Calpain-6 may redistribute to lamellipodia where it regulates RAC1 activity. For IF applications, start with 1:100-1:200 dilution and use methanol fixation or a mild Triton X-100 permeabilization protocol to preserve cytoskeletal structures. Co-staining with alpha-tubulin can help confirm proper localization and validate the staining pattern.

What positive control cell line should I use for Calpain-6 Western blot?

Calpain-6 expression varies significantly across cell types. Neuronal and neurodevelopmental models typically show detectable expression, as CAPN6 plays roles in neural migration and cytoskeletal organization. HEK293 and HeLa cells express moderate levels and serve as accessible positive controls. If endogenous expression is too low in your system, consider transiently transfecting a Calpain-6 expression construct as a positive control to confirm antibody performance at the expected 70-75 kDa. Always include a negative control such as cells treated with CAPN6-specific siRNA to verify band specificity before interpreting experimental results.

Can I use this antibody to distinguish Calpain-6 from other calpain family members?

This polyclonal antibody is raised against Calpain-6-specific sequences and should not cross-react with other calpain family members under standard conditions. The molecular weight difference helps distinguish Calpain-6 (70-75 kDa) from the large subunits of CAPN1 and CAPN2 (80 kDa) and smaller family members. However, polyclonal antibodies can occasionally show off-target binding. To confirm specificity in your experimental system, run a Western blot comparison with lysates from cells overexpressing different calpain isoforms, or use siRNA knockdown of CAPN6 to verify that your band of interest disappears.

How should I store this 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 titer and increase aggregation. The 100 µg pack size allows you to make multiple working aliquots (10-20 µL each) immediately upon receipt. Lyophilized or glycerol-stabilized formulations remain stable for 12-24 months at -20°C. For short-term use (up to one month), diluted antibody in blocking buffer with 0.02% sodium azide can be stored at 4°C and reused for Western blots. Avoid storing diluted antibody without preservative, as this promotes bacterial growth and degradation.