Orphan receptor. Could be involved in a signal transduction pathway controlling epididymal function and male fertility. May regulate fluid exchange within epididymis. Heterodimer of 2 chains generated by proteolytic processing; the large extracellular N-terminal fragment and the membrane-bound C-terminal fragment predominantly remain associated and non-covalently linked. Epididymis-specific expression (at protein level). Associated with apical membranes of efferent ductule and proximal epididymal duct epithelia. Mainly expressed in the nonciliated principal cells of the proximal excurrent ducts. Proteolytically cleaved into 2 subunits, an extracellular subunit and a seven-transmembrane subunit. Highly glycosylated. Mutant male are infertile. Targeted disruption leads to sperm stasis and duct obstruction, resulting from dysregulation of fluid reabsorption. Belongs to the G-protein coupled receptor 2 family. Adhesion G-protein coupled receptor (ADGR) subfamily.