The EGF module-containing Mucin-like hormone Receptors (EMRs) are closely related subgroup of G protein-coupled receptors (GPCRs). These receptors have a unique hybrid structure in which an extracellular epidermal growth factor (EGF)-like domain is fused to a GPCR domain through a mucin-like stalk. There are four variants of EMR labeled 1-4 each encoded by a separate gene. These receptors are predominately expressed in cells of the immune system and bind ligands such as CD55.