Recombinant Human FCRN Protein, CF

Analyzed by SEC-MALS. Non-covalently associated with endogenous beta 2-Microglobulin
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Recombinant Human FCRN Protein SEC-MALS.
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Recombinant Human FCRN Protein, CF Summary

Why choose R&D Systems FCRN Protein?

  • Guaranteed Bioactivity and High Purity: Bioactivity tested by functional ELISA and purity determined by SDS-PAGE to be greater than 95%.
  • Lot-to-Lot Consistency: Stringent QC testing performed on each lot to ensure consistent activity and purity.
  • Bulk Quantities Available: Bulk up and save with large mass quantities to meet your research needs. Supply agreements available, partner with us. Please contact us.
  • Most Respected, Most Cited Brand in Proteins: With over 35 years of providing the best recombinant proteins to the scientific community, R&D Systems continues to lead the industry in quality, activity, and purity.

Product Specifications

>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Endotoxin Level
<0.10 EU per 1 μg of the protein by the LAL method.
Measured by its binding ability in a functional ELISA. When Recombinant Human FCRN is immobilized at 2 µg/mL (100 µL/well), the concentration of biotinylated human IgG that produces 50% of the optimal binding response is approximately 2-10 μg/mL.
Human embryonic kidney cell, HEK293-derived human FCRN protein
Ala24-Ser297, with a C-terminal 6-His tag
Accession #
N-terminal Sequence
Ala24 (FCRN), Ile21 ( beta 2 Microglobulin)
Structure / Form
Non-covalently associated with beta 2 Microglobulin from HEK293 cells.
Predicted Molecular Mass
31 kDa (FCRN), 10 kDa ( beta 2 Microglobulin)
30-36 kDa (FCRN), 10 kDa ( beta 2 Microglobulin)

Product Datasheets

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Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.


Formulation Lyophilized from a 0.2 μm filtered solution in PBS.
Reconstitution Reconstitute at 500 μg/mL in PBS.
Shipping The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after reconstitution.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.

Scientific Data

SEC-MALS View Larger

Recombinant Human FCRN (Catalog # 8639-FC) has a molecular weight (MW) of 45.6 kDa as analyzed by SEC-MALS, suggesting that this protein is a heterodimer.  MW may differ from predicted MW due to post-translational modifications (PTMs) present (i.e. Glycosylation).

Bioactivity Graph showing dose-dependent bioactivity of human FCRN protein View Larger

When recombinant human FCRN (8639-FC) is immobilized at 2 µg/mL (100 µL/well), the concentration of biotinylated human IgG that produces 50% of the optimal binding response is approximately 2-10 μg/mL.

Reconstitution Calculator

Reconstitution Calculator

The reconstitution calculator allows you to quickly calculate the volume of a reagent to reconstitute your vial. Simply enter the mass of reagent and the target concentration and the calculator will determine the rest.


Background: FCRN

The neonatal Fc receptor (FCRN) is an approximately 45 kDa transmembrane glycoprotein with structural homology to MHC class I proteins. It is widely expressed in endothelial and epithelial cells and plays an important role in IgG homeostasis and antigen presentation by dendritic cells (1, 2). Mature human FCRN consists of a 274 amino acid (aa) extracellular domain (ECD) with two N-terminal alpha domains, one alpha 3/immunoglobulin-like domain, a 23 aa transmembrane segment, and a 44 aa cytoplasmic domain (3). Within the ECD, human FCRN shares 68% aa sequence identity with mouse and rat FCRN. Mouse FCRN binds with high affinity to IgG from mouse, human, rat, rabbit, guinea pig, bovine, and sheep, while human FCRN binds IgG with significantly lower affinity and is much more restricted in terms of species recognition (4). It does not bind the structurally related chicken IgY (5). FCRN additionally binds to albumin, and both it and IgG are bound at pH 5.0 but not at pH 8.0 (3, 6). FCRN associates noncovalently with beta 2-Microglobulin, and this interaction is important for the intracellular trafficking of FCRN (7-10). FCRN cycles between the plasma membrane and acidified intracellular compartments of endothelial cells and epithelial cells (5, 8). It binds endocytosed IgG and albumin in the low pH vesicles and transports them to the plasma membrane for extracellular release at higher pH. This protects IgG and albumin from lysosomal degradation and helps maintain the circulating levels of both proteins (5, 6). This mechanism is involved in the bidirectional transport of IgG across epithelial and endothelial barriers including neonatal IgG absorption in the intestine and fetal uptake of maternal antibodies through the placenta (5, 8, 11, 12). In the kidney, FCRN recycles albumin to the serum but removes IgG from the glomular basement membrane and promotes its excretion into the urine (13, 14). FCRN is also expressed in neutrophils and myeloid antigen presenting cells (7, 15, 16). It can enhance IgG-mediated phagocytosis and antigen presentation by these cells, but it promotes the degradation of opsonizing IgG rather than returning it to the circulation (15, 16).

  1. Baker, K. et al. (2009) Semin. Immunopathol. 31:223.
  2. Baker, K. et al. (2014) Front. Immunol. 5:408.
  3. Story, C.M. et al. (1994) J. Exp. Med. 180:2377.
  4. Ober, R.J. et al. (2001) Int. Immunol. 13:1551.
  5. Dickinson, B.L. et al. (1999) J. Clin. Invest. 104:903.
  6. Chaudhury, C. et al. (2003) J. Exp. Med. 197:315.
  7. Simister, N.E. and K.E. Mostov (1989) Nature 337:184.
  8. Kobayashi, N. et al. (2002) Am. J. Physiol. Renal Physiol. 282:F358.
  9. Praetor, A. and W. Hunziker (2002) J. Cell Sci. 115:2389.
  10. Zhu, X. et al. (2001) J. Immunol. 166:3266.
  11. Spiekermann, G.M. et al. (2002) J. Exp. Med. 196:303.
  12. Firan, M. et al. (2001) Int. Immunol. 13:993.
  13. Sarav, M. et al. (2009) J. Am. Soc. Nephrol. 20:1941.
  14. Akilesh, S. et al. (2008) Proc. Natl. Acad. Sci. 105:967.
  15. Vidarsson, G. et al. (2006) Blood 108:3573.
  16. Qiao, S.-W. et al. (2008) Proc. Natl. Acad. Sci. 105:9337.
Long Name
Neonatal Fc Receptor
Entrez Gene IDs
2217 (Human); 14132 (Mouse); 29558 (Rat); 102128913 (Cynomolgus Monkey)
Alternate Names
alpha-chain; Fc fragment of IgG, receptor, transporter, alpha; FCGRT; FcRn alpha chain; FCRN; FCRNimmunoglobulin receptor, intestinal, heavy chain; IgG Fc fragment receptor transporter alpha chain; IgG receptor FcRn large subunit p51; major histocompatibility complex class I-like Fc receptor; Neonatal Fc receptor; neonatal Fc-receptor for Ig

Citations for Recombinant Human FCRN Protein, CF

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

4 Citations: Showing 1 - 4
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  1. Diverging maternal and infant cord antibody functions from SARS-CoV-2 infection and vaccination in pregnancy
    Authors: Adhikari, EH;Lu, P;Kang, YJ;McDonald, AR;Pruszynski, JE;Bates, TA;McBride, SK;Trank-Greene, M;Tafesse, FG;Lu, LL;
    bioRxiv : the preprint server for biology
    Species: Human
    Sample Types: Protein
    Applications: Bioassay
  2. An IgG-based bispecific antibody for improved dual targeting in PSMA-positive cancer
    Authors: L Zekri, F Vogt, L Osburg, S Müller, J Kauer, T Manz, M Pflügler, A Maurer, JS Heitmann, I Hagelstein, M Märklin, S Hörner, T Todenhöfer, C Calaminus, A Stenzl, B Pichler, C la Fougère, MA Schneider, HG Rammensee, L Zender, B Sipos, HR Salih, G Jung
    Embo Molecular Medicine, 2020-12-29;0(0):e11902.
    Species: Human
    Sample Types: Recombinant Protein
    Applications: ELISA Capture
  3. CA125 suppresses amatuximab immune-effector function and elevated serum levels are associated with reduced clinical response in first line mesothelioma patients
    Authors: NC Nicolaides, C Schweizer, EB Somers, W Wang, S Fernando, EN Ross, L Grasso, R Hassan, JB Kline
    Cancer Biol. Ther., 2018-04-25;0(0):1-22.
    Species: Human
    Sample Types: Recombinant Protein
    Applications: ELISA Detection
  4. Glycoengineering of pertuzumab and its impact on the pharmacokinetic/pharmacodynamic properties
    Authors: C Luo, S Chen, N Xu, C Wang, WB Sai, W Zhao, YC Li, XJ Hu, H Tian, XD Gao, WB Yao
    Sci Rep, 2017-04-11;7(0):46347.
    Species: Human
    Sample Types: Pharmaceutical
    Applications: Bioassay


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Recombinant Human FCRN Protein, CF
By Jenna Nguyen on 05/07/2019
Application: CellProlif

Recombinant Human FCRN Protein, CF
By Anonymous on 09/05/2018
Application: Biomarker discovery

Recombinant Human FCRN Protein, CF
By Anonymous on 12/06/2017
Application: Binding assay/Protein-protein interaction