protein_function: Receptor for the Fc region of complexed immunoglobulinsgamma. Low affinity receptor. Involved in a variety of effectorand regulatory functions such as phagocytosis of antigen-antibodycomplexes from the circulation and modulation of antibodyproduction by B-cells. Isoform IIB1 and isoform IIB1" form capsbut fail to mediate endocytosis or phagocytosis. Isoform IIB2 canmediate the endocytosis of soluble immune complexes via clathrin-coated pits. Isoform IIB1 and isoform IIB2 can down-regulate B-cell, T-cell, and mast cell activation when coaggregated to B-cellreceptors for AG (BCR), T-cell receptors for AG (TCR), and Fcreceptors, respectively.
CD32 is a surface receptor protein and part of a large population of B cell co-receptors, which act to modulate signaling. It has a low-affinity for IgG antibodies and down-regulates antibody production in the presence of IgG. This feedback loops essentially lowers the production of IgG produced by B cells when there is a surplus in the body.