Fc Fragment Of IgA Receptor (FcaR)

Only one Fc receptor belongs to the Fc alpha R subgroup, which is called Fc alpha RI (or CD89). Fc alpha RI is found on the surface of neutrophils, eosinophils, monocytes, some macrophages (including Kupffer cells), and some dendritic cells. It is composed of two extracellular Ig-like domains, and is a member of both the immunoglobulin superfamily and the multi-chain immune recognition receptor (MIRR) family. It signals by associating with two FcR gamma，signaling chains.

Another receptor can also bind IgA, although it has higher affinity for another antibody called IgM. This receptor is called the Fc-alpha/mu receptor (Fc alpha/mu R) and is a type I transmembrane protein. With one Ig-like domain in its extracellular portion, this Fc receptor is also a member of the immunoglobulin superfamily.