• FcRn is a specific receptor for IgG and albumin, composed of MHC class I-related molecules and β2-microglobulin. FcRn binds to IgG and albumin in a pH-dependent manner, maintaining the concentration of IgG and albumin in the plasma and facilitating their transmembrane transport. Cells internalize IgG from the serum through endocytosis. Proteins that do not bind to FcRn are degraded in lysosomes, while IgG bound to FcRn is released back into the bloodstream, thereby extending its half-life.
• A chimeric CDS that encodes full-length human FcRn, followed by mouse 3’UTR-STOP, is inserted after mouse FcRn ATG to replace exons 2-4 of mouse FcRn gene. The FcRn protein expression will be driven by the endogenous mouse FcRn promoter, while mouse FcRn gene transcription and translation will be disrupted.
• Mouse FcRn was only detectable in wild-type BALB/cCrSlcNifdc mice. Human FcRn was exclusively detectable in the liver and kidney of homozygous B-hFcRn mice(C).
• Application: This product is used for pharmacokinetics, pharmacodynamics, and safety evaluation of human immunoglobulin G (IgG), and based on the Fc domain therapeutics.

Gene targeting strategy for B-hFcRn mice(C). A chimeric CDS that encodes full-length human FcRn, followed by mouse 3’UTR-STOP, is inserted after mouse FcRn ATG to replace exons 2-4 of the mouse FcRn gene. The FcRn protein expression will be driven by the endogenous mouse FcRn promoter, while mouse FcRn gene transcription and translation will be disrupted.

Western blot analysis of FcRn protein expression in homozygous B-hFcRn mice(C). Various tissue lysates were collected from wild-type BALB/cCrSlcNifdc mice (+/+) and homozygous B-hFcRn mice(C) (H/H), and then analyzed by western blot with species-specific anti-mouse FcRn antibody (R&D, AF6775) and anti-human FcRn antibody (Novus Biologicals, NBP1-89128). 40 μg total protein was loaded for western blotting analysis. Mouse FcRn was only detectable in wild-type BALB/cCrSlcNifdc mice. Human FcRn was exclusively detectable in the liver and kidney of homozygous B-hFcRn mice(C).