Anti-MASP-1 Rabbit Polyclonal Antibody

Frequently Asked Questions

What molecular weight should I expect for MASP-1 on a Western blot?

Full-length MASP-1 zymogen runs at approximately 79–80 kDa on reducing gels. After proteolytic activation, MASP-1 is cleaved into a heavy chain (approximately 56 kDa) and a light chain (approximately 27 kDa) that remain disulfide-linked under non-reducing conditions. In serum or conditioned media from cells expressing MASP-1, you may observe both the zymogen and processed forms. Keep in mind that MASP-3, an alternatively spliced product of the MASP1 gene, shares the heavy chain and migrates around 76 kDa, so confirm your target by expected tissue distribution and functional context.

Does this MASP-1 antibody cross-react with MASP-3 or other complement proteases?

Because MASP-3 is an alternative splice variant of the MASP1 gene and shares the N-terminal CUB and EGF-like domains encoded by common exons, cross-reactivity depends on the epitope recognized by the antibody. This rabbit polyclonal is raised against a region spanning residues 46–460, which includes shared domains. You should expect some recognition of MASP-3. MASP-2, encoded by a separate gene, shares structural homology but is less likely to cross-react. If distinguishing MASP-1 from MASP-3 is critical, validate with recombinant proteins or isoform-specific knockdown controls in your system.

What is the recommended starting dilution for Western blot with this MASP-1 antibody?

We recommend starting at 1:1000 dilution for Western blot applications with this rabbit polyclonal. This dilution has been validated in-house with human serum and lysates from MASP-1-expressing cell lines. MASP-1 is secreted and circulates at low nanomolar concentrations in plasma, so enriched serum or conditioned media typically yield better signals than whole-cell lysates from non-hepatic cells. If signal is weak, you can increase antibody concentration to 1:500, but always titrate against your specific sample type to balance signal and background.

Can I use this antibody to detect MASP-1 in mouse or rat samples?

This antibody has been validated only with human MASP-1. Alignment of the immunogen region shows approximately 85 percent identity between human and mouse MASP-1, so cross-reactivity is possible but not guaranteed. If you intend to work with rodent samples, we recommend first testing the antibody at 1:500 and 1:1000 dilutions on positive-control lysates—mouse liver or serum are reasonable starting points—and running a human sample in parallel. Predicted cross-reactivity does not substitute for empirical validation with your target species.

What sample type and preparation work best for detecting MASP-1?

MASP-1 is a secreted serine protease synthesized primarily in the liver and circulates in plasma complexed with mannan-binding lectin and ficolins. For Western blot, human serum or plasma diluted 1:50 to 1:200 in sample buffer is an excellent positive control. Conditioned medium from hepatocyte cultures or HepG2 cells also works well. Whole-cell lysates from non-hepatic tissues yield lower signals. Avoid boiling samples excessively; 5 minutes at 95°C in reducing buffer is sufficient. If you are studying activation-state changes, consider non-reducing conditions to preserve heavy-light chain disulfide linkages.

How should I store this MASP-1 antibody and how long does it remain stable?

Store the antibody at –20°C in single-use aliquots to avoid repeated freeze-thaw cycles, which can reduce titer and increase aggregation. The antibody is supplied in a glycerol-containing buffer that remains liquid at –20°C, so you may keep a working aliquot at 4°C for up to one month if you use it frequently. Sodium azide at 0.02–0.05 percent can be added to 4°C stocks to prevent microbial growth, but avoid azide if you plan paired immunoprecipitation or functional assays with peroxidase detection. Under these conditions, stability typically exceeds two years from date of manufacture.

What positive and negative controls should I include when validating this MASP-1 antibody?

Human serum or plasma is the most physiologically relevant positive control; dilute 1:100 in sample buffer and run 5–10 µg total protein per lane. Recombinant MASP-1 zymogen or active enzyme also serves as a defined control. For negative controls, consider serum from MASP1-knockout models if available, or pre-immune rabbit IgG at matched concentration on a replicate blot. Lysates from cell lines with low or absent MASP1 expression—such as HeLa or NIH-3T3—help establish background. Always include a molecular-weight ladder spanning 25–100 kDa to confirm identity of zymogen and processed bands.

Can I use this MASP-1 antibody for immunohistochemistry or immunofluorescence?

Triple Point Biologics antibodies are validated for Western blot and immunohistochemistry; this MASP-1 rabbit polyclonal is suitable for IHC on formalin-fixed paraffin-embedded tissue sections. Start with 1:100 to 1:200 dilution and optimize antigen retrieval—citrate buffer pH 6.0 at sub-boiling temperature for 20 minutes is a reasonable first approach. For immunofluorescence on cultured cells or frozen sections, begin at 1:50 to 1:100. Because MASP-1 is secreted, you may see extracellular or perinuclear Golgi staining in hepatocytes. Include isotype-matched control IgG and MASP1-negative tissue to confirm specificity.