FCAR (Fc Fragment of IgA Receptor)
CD89, Fc Alpha Receptor
Gene Information Card
| Symbol | FCAR |
|---|---|
| Full Name | Fc Fragment of IgA Receptor |
| Gene Type | protein-coding |
| Chromosomal Location | 19q13.42 |
| NCBI Gene ID | 2204 ncbi.nlm.nih.gov/gene/2204 |
| Ensembl ID | ENSG00000105369 |
| UniProt ID | P24071 |
| OMIM ID | 147045 |
| HGNC ID | 3618 |
| Aliases | CD89, FcαR, IgA Fc receptor |
Description
The FCAR gene encodes the Fc fragment of IgA receptor (FcαR, CD89), a transmembrane glycoprotein expressed on myeloid cells. It binds the Fc region of IgA antibodies, mediating immune responses such as phagocytosis, antibody-dependent cell-mediated cytotoxicity (ADCC), and inflammatory signaling. Alternative splicing generates multiple isoforms, including soluble forms. FCAR is involved in mucosal immunity and has been implicated in autoimmune diseases and cancer.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| IgA Nephropathy | Altered IgA binding to FcαR on mesangial cells may contribute to immune complex deposition and renal inflammation. | PMID: 25915589; OMIM 147045 |
| Rheumatoid Arthritis | FCAR polymorphisms associated with increased IgA immune complex-mediated inflammation. | PMID: 20405029; ClinVar |
| Systemic Lupus Erythematosus | FCAR variants linked to altered IgA receptor function and autoantibody clearance. | PMID: 21779165; ClinVar |
| Inflammatory Bowel Disease | FCAR expression changes in intestinal mucosa may affect IgA-mediated immune regulation. | PMID: 23076970; NCBI Gene |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Bone Marrow | 12.5 | Medium |
| Spleen | 8.3 | Medium |
| Lung | 5.1 | Low |
| Blood (whole) | 4.7 | Low |
| Liver | 1.2 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| THP-1 (monocyte) | 15.2 | High expression |
| U937 (monocyte) | 12.8 | High expression |
| HL-60 (promyeloblast) | 9.6 | Medium expression |
| K562 (erythroleukemia) | 0.3 | Not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.254G>A (p.Arg85His) | Missense | 0.0012 (gnomAD) | Altered IgA binding affinity |
| c.497C>T (p.Thr166Met) | Missense | 0.0008 (gnomAD) | Potential impact on receptor dimerization |
| c.823G>A (p.Glu275Lys) | Missense | 0.0003 (gnomAD) | Unknown functional effect |
| c.1129+1G>A | Splice donor | <0.0001 | Predicted to disrupt splicing |
Mutation functional classification
Loss of Function (LOF)
Splice-site mutations and missense variants that reduce IgA binding or surface expression (e.g., p.Arg85His) are classified as loss-of-function.
Gain of Function (GOF)
No confirmed gain-of-function mutations reported in FCAR.
Dominant Negative (DN)
Some missense variants may exert dominant-negative effects by disrupting receptor dimerization, but evidence is limited.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Fc gamma R-mediated phagocytosis (KEGG: hsa04666)
• Osteoclast differentiation (KEGG: hsa04380)
• Immune System (Reactome: R-HSA-168256)
Protein Summary
The FCAR protein (CD89) is a type I transmembrane glycoprotein of approximately 55-75 kDa, with an extracellular region containing two immunoglobulin-like domains that bind IgA. It associates with the FcR gamma chain for signaling via ITAM motifs. CD89 is expressed primarily on monocytes, macrophages, neutrophils, and eosinophils. Soluble isoforms generated by alternative splicing or proteolytic cleavage can modulate IgA-mediated immune responses. The receptor plays a key role in mucosal immunity and inflammation.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| FCAR Knockout HEK293 Cell Line | EDJ-KQ4581 | Human | 2204 | Details Get a Quote |
| FCAR Knockout HeLa Cell Line | EDJ-KQ53202 | Human | 2204 | Details Get a Quote |
| FCAR Knockout A-549 Cell Line | EDJ-KQ61683 | Human | 2204 | Details Get a Quote |
| FCAR Knockout HCT 116 Cell Line | EDJ-KQ70169 | Human | 2204 | Details Get a Quote |
