Receptor for the Fc region of immunoglobulins gamma. Low affinity receptor. Binds complexed or aggregated IgG and also monomeric IgG. Contrary to III-A, is not capable to mediate antibody-dependent cytotoxicity and phagocytosis. May serve as a trap for immune complexes in the peripheral circulation which does not activate neutrophils. Monomer. Interacts with INPP5D/SHIP1 (By similarity). Secreted after cleavage. Expressed specifically by polymorphonuclear leukocytes (neutrophils). Also expressed by stimulated eosinophils. Glycosylated. Glycosylation plays an inhibitory role in the interaction with IgG3. The soluble form is produced by a proteolytic cleavage. There are three allelic forms of FCGR3B: FCGR3B*01 (NA-1), FCGR3B*02 (HNA-1b, NA-2) (shown here) and SH. FCGR3B*01 and FCGR3B*02 are detectable with antibodies against the biallelic neutrophil-specific antigen system NA. The more active FCGR3B*01 allele has been associated with severe renal disease in certain systemic vasculitides. Encoded by one of two nearly indentical genes: FCGR3A and FCGR3B (Shown here) which are expressed in a tissue-specific manner. The 'Phe-203' in FCGR3A determines the transmembrane domains whereas the Ser-203 in FCGR3B determines the GPI-anchoring.