EMR1

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EMR1, also called ADGRE1, is a protein on the surface of some immune cells. It belongs to the adhesion GPCR family, with a long outside region that contains EGF-like domains and a single transmembrane segment connected through a GPCR autoproteolysis domain.

In humans, EMR1 is mainly found on eosinophils, making it a useful marker for these cells. In mice, the equivalent protein is F4/80, a well-known marker of macrophages. EMR1 helps regulate the immune response and inflammation.

EMR1 is not required for creating tissue macrophages, but it is involved in processes that support peripheral immune tolerance, including the induction of certain regulatory T cells. Because EMR1 sits on eosinophils and macrophages, it can be targeted with specialized antibodies to deplete these cells in eosinophilic disorders.