FCGR2B
Description
The FCGR2B (Fc gamma receptor IIb) is a protein-coding gene located on chromosome 1.
FCGR2B (Fc fragment of IgG receptor IIb) is a low affinity inhibitory receptor for the Fc region of immunoglobulin gamma (IgG). It participates in the phagocytosis of immune complexes and the regulation of antibody production by B lymphocytes. Two major forms, FCGR2B1 and FCGR2B2, exist due to mRNA splicing, resulting in the inclusion (FCGR2B1) or exclusion (FCGR2B2) of the C1 exon sequence. The presence of the C1 exon in FCGR2B1 tethers it to the membrane of B cells, whereas its absence in FCGR2B2 allows rapid internalization of the receptor in myeloid cells. Both forms contain the Immunoreceptor Tyrosine-based Inhibitory Motif (ITIM) in their cytoplasmic regions. The extracellular domains share 95% identity with FCGR2A domains and are almost identical to FCGR2C domains. FCGR2B is the only inhibitory type I FcγR in humans and mice. FCGR2B1 is highly expressed by B cells, and its mRNA is also found at lower levels on monocytes. FCGR2B2 is highly expressed on basophils and at low levels on monocytes. FCGR2B is co-expressed with the activating FCGRA on circulating myeloid dendritic cells in peripheral blood.
FCGR2B is also known as CD32, CD32B, FCG2, FCGR2, FCGR2C, FcGRIIB, FcRII-c, FcgammaRIIb, IGFR2.
