FCMR
Description
The FCMR (Fc mu receptor) is a protein-coding gene located on chromosome 1.
The FCMR gene encodes the Fc fragment of IgM receptor, a protein that binds to the Fc region of immunoglobulins (Igs) to mediate unique functions for each Ig class. Specifically, FCMR is a receptor for IgM, regulating IgM transport and homeostasis.
The FCMR gene encodes a high-affinity receptor for immunoglobulin M (IgM), interacting with both secreted and membrane-bound IgM. It plays a crucial role in regulating IgM transport and homeostasis. Within lymphoid cells, it facilitates the exocytosis of membrane-bound IgM onto the plasma membrane and the endocytosis of IgM-antigen complexes towards lysosomes for degradation. In mucosal epithelium, FCMR mediates the retrotranscytosis of antigen-IgM complexes across mucosal M cells to antigen-presenting cells in mucosal lymphoid tissues. FCMR triggers costimulatory signaling and mediates most of IgM's effector functions, impacting B cell development and the primary immune response to infection. It likely limits tonic IgM BCR signaling to self-antigens, contributing to the proper negative selection of autoreactive B cells in the bone marrow and the maintenance of the regulatory B cell pool in peripheral lymphoid organs. FCMR also mediates antibody responses to both T cell-dependent and T cell-independent antigens, promoting the induction of an efficient neutralizing IgG response. It engages in cross-talk with antigen-receptor signaling via the non-canonical NF-kappa-B, MAP kinases, and calcium signaling pathways.
FCMR is also known as FAIM3, FcmuR, IgM FcR, TOSO.
Associated Diseases
- common variable immunodeficiency
- isolated agammaglobulinemia
- immunodeficiency 18
- immunodeficiency 62
- immunodeficiency, common variable, 4
- severe combined immunodeficiency due to CTPS1 deficiency
- inborn error of immunity
- BENTA disease
- combined immunodeficiency with skin granulomas
- hyper-IgM syndrome type 2
- hyper-IgM syndrome type 3
- severe combined immunodeficiency due to DCLRE1C deficiency
- severe combined immunodeficiency, autosomal recessive, T cell-negative, B cell-negative, NK cell-positive
- immunodeficiency 72 with autoinflammation
- immunodeficiency 105
