• Species Reactivity

  Human

• Specificity

  Detects human FCRN in direct ELISAs.    
   

• Source

  Monoclonal Mouse IgG    _2B Clone # 937508

• Purification

  Protein A or G purified from hybridoma culture supernatant

• Immunogen

  Chinese hamster ovary cell line CHO-derived recombinant human FCRN    
  Ala24-Ser297    
  Accession # P55899

• Formulation

  Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose. *Small pack size (SP) is supplied as a 0.2 µm filtered solution in PBS.

• Label

  Unconjugated

Applications

• Recommended    
  Concentration

  Sample

• Western Blot

  5 µg/mL

  See below

• 
  

• CyTOF-ready

  Ready to be labeled using established conjugation methods. No BSA or other carrier proteins that could interfere with conjugation.

• 
  

• Intracellular Staining by Flow Cytometry

  0.25 µg/10    ⁶ cells

  See below

• 
  

Please Note: Optimal dilutions should be determined by each laboratory for each application.  are available in the Technical Information section on our website.

Data Examples

Preparation and Storage

• Reconstitution

  Reconstitute at 0.5 mg/mL in sterile PBS.

• Shipping

  The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below. *Small pack size (SP) is shipped with polar packs. Upon receipt, store it immediately at -20 to -70 °C

• 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.

• 6 months, -20 to -70 °C under sterile conditions after reconstitution.

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).

• References:

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)

• 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