EMR1

EGF-like module-containing mucin-like hormone receptor-like 1 also known as F4/80 is a protein encoded by the ADGRE1 gene.
EMR1 is a member of the adhesion GPCR family characterized by an extended extracellular region containing EGF-like domains. EMR1 is predominantly expressed on the surface of macrophages and plays a significant role in immune response modulation and inflammation. Its expression has been linked to various inflammatory diseases.

Structure

Adhesion GPCRs are characterized by an extended extracellular region often possessing N-terminal protein modules that is linked to a TM7 region via a domain known as the GPCR-Autoproteolysis INducing (GAIN) domain.
The N-terminal fragment of EMR1 contains 4-6 Epidermal Growth Factor-like domains in human and 4-7 EGF-like domains in the mouse.

Tissue distribution

EMR1 expression in human is restricted to eosinophils and is a specific marker for these cells. The murine homolog of EMR1, F4/80, is a well-known and widely used marker of murine macrophage populations.

Function

F4/80 is not necessary for the development of tissue macrophages but is required for the induction of efferent CD8⁺ regulatory T cells needed for peripheral tolerance.

Clinical significance

EMR1 can serve as a therapeutic target for depletion of these cells in eosinophilic disorders by using afucosylated antibodies.