Fc epsilon RIA

Fc epsilon RIA, encoded by the FCER1A gene, is the alpha subunit of the high-affinity IgE receptor Fc epsilon RI and provides the ligand-binding function of the receptor complex. Its two extracellular immunoglobulin-like domains engage the Fc portion of IgE, while the transmembrane segment associates with beta and gamma chains that carry the ITAM motifs required for signaling. The alpha chain is expressed on mast cells and basophils and, at lower levels, on eosinophils, Langerhans cells, and other antigen-presenting cells, enabling allergen capture and presentation. FCER1A expression levels correlate with allergic disease severity, and the receptor is a key pharmacological target in IgE-mediated allergy, asthma, and chronic urticaria.