The function of ENSG00000149534 (MS4A2, membrane spanning 4-domains A2) is as follows. High affinity receptor that binds to the Fc region of immunoglobulins epsilon. Aggregation of FCER1 by multivalent antigens is required for the full mast cell response, including the release of preformed mediators (such as histamine) by degranulation and de novo production of lipid mediators and cytokines. Also mediates the secretion of important lymphokines. Binding of allergen to receptor- bound IgE leads to cell activation and the release of mediators responsible for the manifestations of allergy.