FCMR: Fc Receptor for IgM (FcμR)
A key immune receptor for IgM, involved in B cell regulation and immune homeostasis.
Gene Information Card
| Symbol | FCMR |
|---|---|
| Full Name | Fc fragment of IgM receptor |
| Gene Type | protein-coding |
| Chromosomal Location | 1q32.1 |
| NCBI Gene ID | 9214 ncbi.nlm.nih.gov/gene/9214 |
| Ensembl ID | ENSG00000162894 |
| UniProt ID | Q00604 |
| OMIM ID | 606015 |
| HGNC ID | 3624 |
| Aliases | FcμR, FAIM3, TOSO |
Description
FCMR (Fc fragment of IgM receptor) encodes the Fc receptor for IgM (FcμR), a transmembrane protein expressed primarily on B cells, T cells, and natural killer cells. It binds the Fc region of IgM antibodies and plays a critical role in B cell survival, proliferation, and immune regulation. The gene is located on chromosome 1q32.1 and is also known as FAIM3 or TOSO.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Chronic Lymphocytic Leukemia (CLL) | Overexpression of FCMR in malignant B cells may promote survival and resistance to apoptosis. | ClinVar, COSMIC |
| Systemic Lupus Erythematosus (SLE) | Polymorphisms in FCMR are associated with altered IgM-mediated immune regulation. | OMIM, NCBI |
| Immunodeficiency | Loss-of-function mutations in FCMR impair B cell responses to IgM, leading to recurrent infections. | ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Spleen | 45.2 | High |
| Lymph node | 38.7 | High |
| Bone marrow | 22.1 | Medium |
| Blood | 18.5 | Medium |
| Lung | 5.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Raji (Burkitt lymphoma) | 62.4 | B cell line, high expression |
| Daudi (Burkitt lymphoma) | 58.1 | B cell line, high expression |
| Jurkat (T cell leukemia) | 12.3 | T cell line, moderate expression |
| HEK293 (embryonic kidney) | 1.2 | Non-immune cell line, low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.497G>A (p.Arg166Gln) | Missense | 0.01% | Reduced IgM binding affinity |
| c.112C>T (p.Arg38*) | Nonsense | <0.01% | Loss of function, truncated protein |
| c.784_785insA (p.Thr262Asnfs*5) | Frameshift | <0.01% | Loss of function, premature stop |
Mutation functional classification
Loss of Function (LOF)
Nonsense and frameshift mutations (e.g., p.Arg38*, p.Thr262Asnfs*5) lead to truncated or absent protein, impairing IgM binding and B cell signaling.
Gain of Function (GOF)
Not reported in FCMR.
Dominant Negative (DN)
Not reported in FCMR.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Fc receptor signaling pathway (Reactome: R-HSA-2029481)
• B cell receptor signaling pathway (KEGG: hsa04662)
Protein Summary
The FCMR protein (FcμR) is a type I transmembrane glycoprotein of 390 amino acids. It contains an extracellular Ig-like domain that binds the Fc region of IgM, a transmembrane domain, and a cytoplasmic tail with signaling motifs. FcμR is expressed on B cells, T cells, and NK cells, and modulates B cell activation, survival, and antibody production. Its dysregulation is implicated in B cell malignancies and autoimmune diseases.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| FCMR Knockout HEK293 Cell Line | EDJ-KQ2821 | Human | 9214 | Details Get a Quote |
| FCMR Knockout A-549 Cell Line | EDJ-KQ23792 | Human | 9214 | Details Get a Quote |
| FCMR Knockout HeLa Cell Line | EDJ-KQ23793 | Human | 9214 | Details Get a Quote |
| FCMR Knockout HCT 116 Cell Line | EDJ-KQ72051 | Human | 9214 | Details Get a Quote |
