Receptor for the invariable Fc fragment of immunoglobulin gamma (IgG) (PubMed:16039578). Binds with intermediate affinity to both IgG2a and IgG2b (PubMed:16039578, PubMed:17558411, PubMed:19795417). Can bind to IgG2a and IgG2b monomers (PubMed:18949059). Does not display binding to IgG1 or IgG3 (PubMed:16039578). Recognizes neutralizing virus-specific IgGs displayed on the cell surface of infected cells and triggers antibody-dependent cellular cytotoxicity (ADCC). Confers protection to lethal influenza virus infection (PubMed:24412922). On splenic dendritic cells, uptakes antigen immune complexes and efficiently divert them into MHC class I and II antigen presentation pathways to provide for superior priming of CD4-positive and CD8-positive T cell immune responses (PubMed:28389502). Mediates neutrophil activation by IgG complexes redundantly with FCGR2A (PubMed:18097064). Plays a role in promoting bone resorption by enhancing osteoclast differentiation following binding to IgG2a (PubMed:25824719). Also acts as a receptor for the Fc region of immunoglobulin epsilon (IgE) (PubMed:17558411, PubMed:18949059). Binds with low affinity to both the a and b allotypes of IgE (PubMed:18949059). Has also been shown to bind to IgE allotype a only but not to allotype b (PubMed:17558411). Binds aggregated IgE but not the monomeric form and bound monomeric IgG is readily displaced by IgE complexes (PubMed:18949059). Binding to IgE promotes macrophage-mediated phagocytosis, antigen presentation to T cells, production of pro-inflammatory cytokines and the late phase of cutaneous allergic reactions (PubMed:17558411, PubMed:18949059). Mediates enhanced ADCC in response to afucosylated IgGs (PubMed:34485821). Forms a heterooligomeric complex with ITAM-containing signaling subunits FCER1G. Interacts (via transmembrane domain) with signaling subunits; this interaction is a prerequisite for receptor complex expression on the cell surface and intracellular signal transduction. Binds the Fc region of antigen-complexed IgG. Detected on myeloid cells, peripheral blood monocytes, splenic and bone marrow dendritic cells, and thioglycollate-elicited macrophages and neutrophils but absent from lymphoid populations with no expression observed on T cells, B cells, NK cells or other granulocytes (at protein level) (PubMed:16039578, PubMed:19795417). Expressed in peripheral blood leukocytes, spleen, liver, thymus and small intestine (PubMed:12389094, PubMed:17558411). Expressed in splenic dendritic cell subsets (at protein level). By lipopolysaccharide, interferon beta and IFNG. N-glycosylated. Phosphorylated following receptor ligation.