FCGR2B

FCGR2B or Fc gamma receptor IIb is a protein that in humans is encoded by the FCGR2B gene. It is a member of the immunoglobulin superfamily and is a low affinity receptor for the Fc region of immunoglobulin G (IgG). This gene is highly polymorphic, with several known variations that affect the function of the protein and the immune response.

Structure

The FCGR2B protein is a single-pass type I membrane protein, with an extracellular region that contains two immunoglobulin-like domains. The cytoplasmic region contains an immunoreceptor tyrosine-based inhibitory motif (ITIM), which is critical for its inhibitory function.

Function

FCGR2B plays a crucial role in the immune response. It is an inhibitory receptor that is expressed on B cells, macrophages, mast cells, and dendritic cells. When it binds to the Fc region of IgG, it inhibits cellular responses such as phagocytosis, cytokine release, and antibody production. This helps to regulate the immune response and prevent overactivation, which can lead to autoimmune diseases.

Clinical significance

Mutations in the FCGR2B gene have been associated with susceptibility to systemic lupus erythematosus (SLE), a chronic autoimmune disease. Some variations in the gene can lead to a decrease in the inhibitory function of the receptor, resulting in an overactive immune response and increased risk of SLE.

See also

• Fc gamma receptors
• Immunoglobulin G
• Systemic lupus erythematosus