FCGR3B

FCGR3B (also known as CD16b or FcγRIIIb) is a gene that encodes for a receptor found on the surface of certain immune cells, specifically neutrophils. This receptor plays a crucial role in the immune response by binding to the Fc portion of immunoglobulin G (IgG) antibodies, thus facilitating the process of phagocytosis.

Structure

The FCGR3B gene is located on the short arm of chromosome 1 (1p36.11). It encodes a protein of 233 amino acids, which forms a transmembrane receptor. The receptor is a glycoprotein with a molecular weight of approximately 50-80 kDa. It is a low affinity receptor, meaning it binds to IgG antibodies only when they are part of an immune complex.

Function

The primary function of FCGR3B is to mediate the process of phagocytosis in neutrophils. When an antibody binds to a pathogen, the Fc portion of the antibody is exposed. This exposed portion can then be recognized and bound by the FCGR3B receptor. This binding triggers a series of intracellular signals that lead to the engulfment and destruction of the pathogen.

Clinical significance

Alterations in the FCGR3B gene have been associated with various autoimmune diseases, including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). In these conditions, the immune system mistakenly attacks the body's own tissues. Studies have shown that individuals with certain FCGR3B gene variants are more likely to develop these diseases.

See also

• Fc receptor
• Neutrophil
• Immunoglobulin G
• Phagocytosis