Recombinant Mouse CXADR/CAR Fc Chimera Protein, CF

CXADR (coxsackie and adenovirus receptor), also known as CAR, is a 46 kDa type I transmembrane glycoprotein that belongs to the CTX family of the Ig superfamily (1 - 3). CXADR has received attention as a receptor that facilitates gene transfer mediated by most adenoviruses (1, 2). It is also an adhesion molecule within junctional complexes, notably between epithelial cells lining body cavities and within myocardial intercalated discs (1, 2, 4). CXADR is essential for normal cardiac development in the mouse (7). It is expressed throughout brain neuroepithelium during development, but mainly in ependymal cells in the adult (4 - 6). The 365 amino acid (aa) mouse CXADR contains a 19 aa signal sequence, a 218 aa extracellular domain (ECD) with a V-type (D1) and a C2-type (D2) Ig-like domain, a 21 aa transmembrane segment and a 107 aa intracellular domain. D1 is thought to be responsible for homodimer formation in trans within tight junctions (2). The fiber knob of adenoviruses attaches at a similar site, and evidence suggests that disruption of tight junctions facilitates virus binding (1, 2). A PDZ binding motif at the C-terminus interacts with several cytoplasmic junctional proteins (1). The ECD of mouse CXADR shares 97%, 90%, 89%, 89% and 88% aa sequence identity with the corresponding regions of rat, human, bovine, porcine and canine CXADR, respectively. An alternately spliced isoform (CXADR2) that diverges in the C-terminal 15 aa shows the same expression pattern, but may show different subcellular localization (4, 8). Transcription of other splice variants has been detected, but not their translation. A secreted form identified in serum and pleural fluid can block viral infection (9).