Adapter protein containing an immunoreceptor tyrosine-based activation motif (ITAM) that transduces activation signals from various immunoreceptors. As a component of the high-affinity immunoglobulin E (IgE) receptor, mediates allergic inflammatory signaling in mast cells. As a constitutive component of interleukin-3 receptor complex, selectively mediates interleukin 4/IL4 production by basophils priming T-cells toward effector T-helper 2 subset. Associates with pattern recognition receptors CLEC4D and CLEC4E to form a functional signaling complex in myeloid cells. Binding of mycobacterial trehalose 6,6'-dimycolate (TDM) to this receptor complex leads to phosphorylation of ITAM, triggering activation of SYK, CARD9 and NF-kappa-B, consequently driving maturation of antigen-presenting cells and shaping antigen-specific priming of T-cells toward effector T-helper 1 and T-helper 17 cell subtypes. May function cooperatively with other activating receptors. Functionally linked to integrin beta-2/ITGB2-mediated neutrophil activation. Also involved in integrin alpha-2/ITGA2-mediated platelet activation. IgE Fc receptor is a tetramer of an alpha chain, a beta chain, and two disulfide linked gamma chains. Associates with FCGR1A to form a functional receptor complex (By similarity). The signaling subunit of immunoglobulin gamma (IgG) Fc receptor complex. As a homodimer or a heterodimer of CD247 and FCER1G, associates with the ligand binding subunit FCGR3A to form a functional receptor complex (PubMed:1825220). Associates with CLEC6A. Interacts with CLEC4E (PubMed:23921530). Interacts (via ITAM domain) with SYK (via SH2 domains); activates SYK, enabling integrin-mediated activation of neutrophils and macrophages (By similarity). Interacts with common beta chain of interleukin 3 receptor CSF2RB and recruits SYK in response to IL3 stimulation; this interaction is direct (By similarity). Interacts with CD300LH; the interaction may be indirect. Interacts with CD300LD (By similarity). Interacts with TARM1 (By similarity). Expressed in leukocytes and pinealocytes. Expression in the pineal gland does not undergo circadian variations. Belongs to the CD3Z/FCER1G family.