Binds to the Fc region of immunoglobulins epsilon. High affinity receptor. Responsible for initiating the allergic response. Binding of allergen to receptor-bound IgE leads to cell activation and the release of mediators (such as histamine) responsible for the manifestations of allergy. The same receptor also induces the secretion of important lymphokines. Tetramer of an alpha chain, a beta chain, and two disulfide linked gamma chains. Expressed in bone marrow mast cells, as well as in the pineal gland at night. Exhibits night/day variations with an increased expression at night in the pineal gland.