Nectin-4 (PVRL4) is a type I transmembrane glycoprotein which belongs to the nectin family of Ig superfamily proteins. It contains two Ig-like C2-type domains and one Ig-like V-type domain. PVRL4 seems to be involved in cell adhesion through trans-homophilic and -heterophilic interactions, the latter including specifically interactions with nectin-1. It does not act as receptor for alpha-herpesvirus entry into cells. It is predominantly expressed in placenta, the embryo and breast carcinoma. But it is not detected in normal breast epithelium. The soluble form is produced by proteolytic cleavage at the cell surface (shedding), probably by ADAM17. Mutations in this gene are the cause of ectodermal dysplasia-syndactyly syndrome type 1, an autosomal recessive disorder.