Coxsackie virus and adenovirus receptor (CXADR), also known as CAR, is a type I transmembrane glycoprotein that serves as a receptor for group B coxsackie viruses and subgroup C adenoviruses. It belongs to the CTX family within the immunoglobulin (Ig) superfamily. CAR is strongly expressed in the developing central nervous system and functions as both a homophilic and heterophilic cell adhesion molecule through its interactions with extracellular matrix glycoproteins, including fibronectin, agrin, laminin-1, and tenascin-R.
The human CXADR protein consists of a signal sequence, an extracellular domain (ECD) with a V-type (D1) and a C2-type (D2) Ig-like domain, a transmembrane segment, and an intracellular domain. The D1 domain is believed to be responsible for homodimer formation within tight junctions and is necessary and sufficient for adenovirus binding. Variants of CXADR are anchored to the cell membrane by a glycosylphosphatidylinositol (GPI) anchor.