CXADR (coxsackie virus and adenovirus receptor), also known as CAR, is a type I transmembrane glycoprotein belonging to the CTX family within the immunoglobulin (Ig) superfamily. It plays a critical role in normal cardiac development in mice. Proposed to function as a homophilic cell adhesion molecule, CXADR is a component of the epithelial apical junction complex, essential for maintaining tight junction integrity and likely involved in the transepithelial migration of polymorphonuclear leukocytes (PMNs).
The mature mouse CXADR structure comprises 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.