Figure 3.

The human FcγR family. FcγRIA, FcγRIIA/IIC and FcγRIIIA initiate activating signalling pathways via immune tyrosine-based activation motifs (ITAMs, highlighted in green), whereas FcγRIIB is an inhibitory FcγR carrying an immune tyrosine-based activation motif (ITIM, highlighted in red). FcγRIII lacks a signalling domain. The strength of the signal mediated through both activating and inhibitory FcγRs, which are often co-expressed on inflammatory immune cells, sets the threshold for the initiation of FcγR-dependent effector responses.