Pig FcRn heterodimer Protein (In Vivo Grade, Ultra-Low Endotoxin) (ICH3024)

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This product is a recombinant pig (Sus scrofa domesticus) FcRn heterodimer, comprising the FcRn heavy chain (FCGRT, UniProt E9LK24) co-expressed with beta-2-microglobulin (B2M, UniProt Q07717) in HEK293 cells. Mammalian expression supports native folding, disulfide formation and the correct heavy-chain/beta-2-microglobulin pairing required for pH-dependent IgG and albumin binding, making it well suited to biophysical and biochemical characterization rather than cell-based assays. It is validated for label-free interaction analysis by surface plasmon resonance (SPR) and biolayer interferometry (BLI), and for ELISA. Typical applications include measuring pH-dependent Fc-FcRn affinity and off-rates for therapeutic antibodies and Fc-fusion proteins, screening Fc engineering variants intended to modulate half-life, and cross-species comparison in translational and veterinary programs where pig is a relevant preclinical model. The protein is produced as a bulk, ultra-low-endotoxin, in-vivo-grade research reagent (RUO), enabling reproducible use across screening campaigns. All content here is guidance for ichorbio to review before publishing. The neonatal Fc receptor (FcRn) is an MHC class I-like molecule composed of a transmembrane heavy chain (FCGRT, UniProt E9LK24) non-covalently associated with beta-2-microglobulin (B2M, UniProt Q07717). Unlike classical MHC class I, FcRn does not present peptide; instead its heavy chain forms a shallow groove that engages the CH2-CH3 interface of IgG-Fc and, at a distinct site, serum albumin, in a strictly pH-dependent manner (binding at acidic endosomal pH ~6.0, release at neutral pH ~7.4). This pH switch underlies FcRn's two central roles: rescuing pinocytosed IgG and albumin from lysosomal degradation to extend their serum half-life, and transcytosing IgG across epithelial and endothelial barriers. In pig, FcRn additionally mediates transfer of maternal IgG from colostrum across neonatal intestinal epithelium, conferring passive immunity.