CXADR （coxsackie virus and adenovirus receptor）, also known as CAR, is a type I transmembrane glycoprotein that belongs to the CTX family within the immunoglobulin （Ig） superfamily. It is crucial for normal cardiac development in mice. CXADR is proposed to function as a homophilic cell adhesion molecule and is a component of the epithelial apical junction complex, which is essential for maintaining tight junction integrity. It is also likely involved in the transepithelial migration of polymorphonuclear leukocytes （PMNs）.
The mature mouse CXADR structure consists of a 218 amino acid （aa） extracellular domain （ECD）, which includes a V-type （D1） and a C2-type （D2） Ig-like domain, a 21 aa transmembrane segment, and a 17 aa intracellular domain. Notably, D1 is believed to be responsible for homodimer formation within tight junctions. The ECD of mouse CXADR shares 97% sequence identity with the corresponding regions of human CXADR and 9% sequence identity with those of rat CXADR.