EMR

EMR may refer to:

EMR2

EGF-like module-containing mucin-like hormone receptor-like 2 also known as CD312 (cluster of differentiation 312) is a protein encoded by the ADGRE2 gene. EMR2 is a member of the adhesion GPCR family. 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.

EMR2 is expressed by monocytes/macrophages, dendritic cells and all types of granulocytes. In the case of EMR2 the N-terminal domains consist of alternatively spliced epidermal growth factor-like (EGF-like) domains. EMR2 is closely related to CD97 with 97% amino-acid identity in the EGF-like domains. The N-terminal fragment (NTF) of EMR2 presents 2-5 EGF-like domains in human. Mice lack the Emr2 gene. This gene is closely linked to the gene encoding EGF-like molecule containing mucin-like hormone receptor 3 EMR3 on chromosome 19.

Ligand

Like the related CD97 protein, the fourth EGF-like domain of EMR2 binds chondroitin sulfate B to mediate cell attachment. However, unlike CD97 EMR2 does not interact with the complement regulatory protein, decay accelerating factor CD55, and indicating that these very closely related proteins likely have nonredundant functions.

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. 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.

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. The N-terminal fragment (NTF) of EMR1 contains 4-6 Epidermal Growth Factor-like (EGF-like) domains in human and 4-7 EGF-like domains in the mouse.

Function

Utilizing F4/80 knockout mice, Lin et al. showed that 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

Legrand et al. recently demonstrated that EMR1 can serve as a therapeutic target for depletion of these cells in eosinophilic disorders by using afucosylated antibodies.