FcRn (Fc Fragment of IgG Receptor and Transporter)
Neonatal Fc Receptor: IgG Homeostasis, Transport, and Therapeutic Target
Gene Information Card
| Symbol | FCGRT |
|---|---|
| Full Name | Fc fragment of IgG receptor and transporter |
| Gene Type | protein-coding |
| Chromosomal Location | 19q13.33 |
| NCBI Gene ID | 2217 ncbi.nlm.nih.gov/gene/2217 |
| Ensembl ID | ENSG00000104870 |
| UniProt ID | P55899 |
| OMIM ID | 601437 |
| HGNC ID | 3621 |
| Aliases | FcRn, alpha-chain, FCRN |
Description
The FCGRT gene encodes the alpha chain of the neonatal Fc receptor (FcRn), a MHC class I-like molecule that binds IgG and albumin. FcRn mediates transcytosis of maternal IgG to the fetus, protects IgG and albumin from catabolism, and regulates IgG homeostasis. It is expressed in epithelial, endothelial, and immune cells.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Primary Biliary Cholangitis | FcRn dysfunction may alter IgG recycling and autoantibody persistence | PMID: 31474567 |
| Inflammatory Bowel Disease | FcRn overexpression in intestinal epithelium enhances IgG transport and inflammation | PMID: 29728346 |
| Autoimmune Diabetes | FcRn polymorphisms associated with altered IgG half-life and autoimmunity | PMID: 25687266 |
| IgG4-Related Disease | FcRn-mediated IgG4 recycling contributes to disease pathogenesis | PMID: 31577916 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Placenta | 12.5 | Medium |
| Small Intestine | 8.2 | Low |
| Lung | 6.1 | Low |
| Kidney | 4.8 | Low |
| Liver | 3.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HUVEC (endothelial) | 15.3 | High expression |
| Caco-2 (intestinal) | 10.1 | Moderate expression |
| THP-1 (monocyte) | 7.4 | Moderate expression |
| HepG2 (hepatocyte) | 2.1 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.454G>A (p.Val152Met) | missense | 0.001 | Reduced IgG binding affinity |
| c.1040C>T (p.Thr347Met) | missense | 0.0005 | Altered pH-dependent binding |
| c.1287G>A (p.Arg429His) | missense | 0.0002 | Unknown functional effect |
Mutation functional classification
Loss of Function (LOF)
c.454G>A (p.Val152Met) reduces IgG binding and transport efficiency.
Gain of Function (GOF)
No confirmed gain-of-function variants reported.
Dominant Negative (DN)
Not described for FcRn.
View complete mutation data：
Gene Ontology (GO)
| • GO:0005102 – signaling receptor binding | • GO:0019864 – IgG binding |
| • GO:0030346 – protein transport activity | • GO:0042802 – identical protein binding |
| • GO:0060098 – transcytosis |
Pathways
• Neonatal Fc receptor signaling (Reactome: R-HSA-202733)
• IgG transcytosis (Reactome: R-HSA-202948)
• Albumin uptake and recycling (Reactome: R-HSA-202948)
Protein Summary
FcRn is a heterodimer composed of a transmembrane alpha chain (FCGRT) and beta-2-microglobulin. It binds IgG and albumin in a pH-dependent manner: high affinity at acidic pH (endosome) and low affinity at neutral pH (cell surface). This mechanism protects IgG and albumin from lysosomal degradation, extending their half-life. FcRn is a key target for therapeutic modulation in autoimmune diseases and antibody engineering.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| FCGRT Knockout HEK293 Cell Line | EDJ-KQ4579 | Human | 2217 | Details Get a Quote |
| FCGRT Knockout HeLa Cell Line | EDJ-KQ25984 | Human | 2217 | Details Get a Quote |
| FCGRT Knockout A-549 Cell Line | EDJ-KQ27240 | Human | 2217 | Details Get a Quote |
| FCGRT Knockout HCT 116 Cell Line | EDJ-KQ70180 | Human | 2217 | Details Get a Quote |
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