The epidermal growth factor (EGF) family constitutes a group of class B, G protein-coupled receptors, which includes CD97 and EMR2. EMR2 is a member of the EGF-TM7 receptor subfamily. EGF-TM7 receptors are a family of class B, seven-span transmembrane (TM7) receptors predominantly expressed by cells of the immune system. Within the TM7 superfamily, the molecular structure and ligand-binding properties of EGF-TM7 receptors are unique. Derived from the processing of a single polypeptide, they are expressed at the cell surface as heterodimers consisting of a large extracellular region associated with a TM7 moiety. Through a variable number of N-terminal EGF-like domains, EGF-TM7 receptors interact with cellular ligands such as CD55 and chondroitin sulfate. EMR2 is a heptahelical molecule predominantly expressed on cells of the immune system such as leukocytes. EMR2 is proteo-lytically cleaved into two separate subunits: a seven-transmembrane subunit, and an extracellular Alpha subunit.