Recombinant Human APCS (PTX2) (carrier-free)

Pricing & Availability
Regulatory Status
Other Names
Amyloid P component, serum, Serum Amyloid P (SAP), Pentraxin 2 (PTX2), HEL-S-92n
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Product Citations
Recombinant human APCS is able to bind to immobilized HDL (50 µg/ml) in a dose dependent manner. The ED50 = 0.24 - 0.96 µg/ml.
  • APCS_Human_RECOM_BA_092914
    Recombinant human APCS is able to bind to immobilized HDL (50 µg/ml) in a dose dependent manner. The ED50 = 0.24 - 0.96 µg/ml.
  • Human_APCS_CF_RECOM_072420.png
    When recombinant human CD32α (Cat. No. 781404) is immobilized at 2 µg/mL, recombinant human APCS binds in a dose-dependent manner. The EC50 range for this effect is 20 - 100 ng/mL.
Cat # Size Price Save
556604 25 µg ¥38,560
556606 100 µg ¥113,400

APCS (amyloid P component, serum), also known as pentraxin 2 (PTX2), is a member of the pentraxin family, which has a characteristic non-covalently linked pentameric organization. This protein is characterized by its calcium-dependent ligand binding and distinctive flattened β-jellyroll structure similar to legume lectins. Human APCS shares a 79% amino acid homology with its mouse counterpart. APCS is secreted by hepatocytes as part of the acute phase protein synthesys in response to infections. Upon binding to its ligands, APCS is involved in the activation of classical complement cascade. In a mouse model, APCS was shown to downregulate acute inflammation accompanying experimental autoimmune encephalomyelitis by regulating T cell activity. Besides its role in regulating immune response, APCS is found to be a component of amyloid deposits, which has the ability of stabilizing amyloid fibrils and protecting them from proteolytic degradation. Based on these studies, it was postulated that APCS may play a role in Alzheimer's disease and other amyloidoses. Interestingly, APCS is also identified as a component of basement membrane proteins, and is able to bind laminin, collagen IV, P-selectin, and fibronectin in a Ca2+ dependent manner. In addition, APCS is known to specifically localize in human atherosclerotic lesions, which suggests that it may play a role in atherogenesis. Functional studies revealed that APCS binds to lipoproteins, specifically to HDL, but not LDL.

Product Details
Technical data sheet

Product Details

Human APCS, amino acids (His20-Val223) (Accession# NP_001630), was expressed with a C-terminal His tag and a linker sequence in 293E cells.
Molecular Mass
The 219 amino acid recombinant protein has a predicted molecular mass of approximately 25 kD. The protein migrates at 27 kD in DTT-reducing conditions by SDS-PAGE. The predicted N-terminal amino acid is His.
>95%, as determined by Coomassie stained SDS-PAGE.
0.22 µm filtered protein solution is in PBS, pH 7.2.
Endotoxin Level
Less than 1.0 EU per µg of protein as determined by the LAL method.
10 and 25 µg sizes are bottled at 200 µg/mL. 100 µg size is lot-specific and bottled at the concentration indicated on the vial. To obtain lot-specific concentration, please enter the lot number in our Concentration and Expiration Lookup or Certificate of Analysis online tools.
Please note, new lots of the 100 µg size will be lot-specific and may differ from previous lots that had a fixed concentration.
Storage & Handling
Unopened vial can be stored between 2°C and 8°C for up to 2 weeks, at -20°C for up to six months, or at -70°C or colder until the expiration date. For maximum results, quick spin vial prior to opening. The protein can be aliquoted and stored at -20°C or colder. Stock solutions can also be prepared at 50 - 100 µg/mL in appropriate sterile buffer, carrier protein such as 0.2 - 1% BSA or HSA can be added when preparing the stock solution. Aliquots can be stored between 2°C and 8°C for up to one week and stored at -20°C or colder for up to 3 months. Avoid repeated freeze/thaw cycles.
Human APCS is able to bind immobilized HDL (50 µg/ml) in a dose dependent manner with a half maximum binding of ED50 = 0.24 - 0.96 µg/ml.

When recombinant human CD32α (Cat. No. 781404) is immobilized at 2 µg/mL, recombinant human APCS binds in a dose-dependent manner. The EC50 range for this effect is 20 - 100 ng/mL.


Application Notes

HDL at 50 µg/ml in 50 mM Tris, 150 mM NaCl, 1 mM CaCl2, and in pH 7.4 (100 µL/well) was immobilized in an ELISA plate and used in the binding assay.1

BioLegend carrier-free recombinant proteins provided in liquid format are shipped on blue-ice. Our comparison testing data indicates that when handled and stored as recommended, the liquid format has equal or better stability and shelf-life compared to commercially available lyophilized proteins after reconstitution. Our liquid proteins are verified in-house to maintain activity after shipping on blue ice and are backed by our 100% satisfaction guarantee. If you have any concerns, contact us at

Application References

(PubMed link indicates BioLegend citation)
  1. Li XA, et al. 1998. Biochem. Biophys. Res. Commun. 244:249.

Antigen Details



APCS recognizes microbial pathogens and activates the classical complement pathway. It binds to Fcγ receptors and opsonizes particles for phagocytosis.
Cells expressing Fcγ receptors.
FcγR (CD16, CD32, and CD64), collegen IV, laminin, HDL, VLDL, fibronectin, CRP, and CD62L.
Human APCS is able to bind HDL in a dose dependent manner in the presence of Ca2+.
Biology Area
Complement, Innate Immunity, Neuroinflammation, Neuroscience
Molecular Family
Antigen References

1. Tennent GA, et al. 1995. Proc. Natl. Acad. Sci. USA. 92:4299.
2. Li XA, et al. 1998. Biochem. Biophys. Res. Commun. 244:249.
3. Zahedi K. 1996. J. Biol. Chem. 271:14897.
4. Pepys M, et al. 2002. Nature 417:254.
5. Stibenz D, et al. 2006. Eur. J. Immunol. 36:446.
6. Lu J, et al. 2008. Nature 456:989.

Gene ID
325 View all products for this Gene ID
View information about APCS on

Related FAQs

Why choose BioLegend recombinant proteins?

     • Each lot of product is quality-tested for bioactivity as indicated on the data sheet.
     • Greater than 95% Purity or higher, tested on every lot of product.
     • 100% Satisfaction Guarantee for quality performance, stability, and consistency.
     • Ready-to-use liquid format saves time and reduces challenges associated with reconstitution.
     • Bulk and customization available. Contact us.
     • Learn more about our Recombinant Proteins.

How does the activity of your recombinant proteins compare to competitors?

We quality control each and every lot of recombinant protein. Not only do we check its bioactivity, but we also compare it against other commercially available recombinant proteins. We make sure each recombinant protein’s activity is at least as good as or better than the competition’s. In order to provide you with the best possible product, we ensure that our testing process is rigorous and thorough. If you’re curious and eager to make the switch to BioLegend recombinants, contact your sales representative today!

What is the specific activity or ED50 of my recombinant protein?

The specific activity range of the protein is indicated on the product datasheets. Because the exact activity values on a per unit basis can largely fluctuate depending on a number of factors, including the nature of the assay, cell density, age of cells/passage number, culture media used, and end user technique, the specific activity is best defined as a range and we guarantee the specific activity of all our lots will be within the range indicated on the datasheet. Please note this only applies to recombinants labeled for use in bioassays. ELISA standard recombinant proteins are not recommended for bioassay usage as they are not tested for these applications.

Have your recombinants been tested for stability?

Our testing shows that the recombinant proteins are able to withstand room temperature for a week without losing activity. In addition the recombinant proteins were also found to withstand four cycles of freeze and thaw without losing activity.

Does specific activity of a recombinant protein vary between lots?

Specific activity will vary for each lot and for the type of experiment that is done to validate it, but all passed lots will have activity within the established ED50 range for the product and we guarantee that our products will have lot-to-lot consistency. Please conduct an experiment-specific validation to find the optimal ED50 for your system.

How do you convert activity as an ED50 in ng/ml to a specific activity in Units/mg?
Use formula Specific activity (Units/mg) = 10e6/ ED50 (ng/mL)
Go To Top Version: 2    Revision Date: 05/21/2015

For research use only. Not for diagnostic use. Not for resale. BioLegend will not be held responsible for patent infringement or other violations that may occur with the use of our products.


*These products may be covered by one or more Limited Use Label Licenses (see the BioLegend Catalog or our website, BioLegend products may not be transferred to third parties, resold, modified for resale, or used to manufacture commercial products, reverse engineer functionally similar materials, or to provide a service to third parties without written approval of BioLegend. By use of these products you accept the terms and conditions of all applicable Limited Use Label Licenses. Unless otherwise indicated, these products are for research use only and are not intended for human or animal diagnostic, therapeutic or commercial use.


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Toll-Free Phone: 1-877-Bio-Legend (246-5343) Phone: (858) 768-5800 Fax: (877) 455-9587


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