Coxsackievirus and adenovirus receptor (CAR) is a protein that in humans is encoded by the CXADRgene. The protein encoded by this gene is a type I membrane receptor for group B coxsackie viruses and subgroup C adenoviruses. The human CAR gene (CXADR) is found on chromosome 21. Alternative splicing is known to produce at least 2 splice variants known as hCAR1 and hCAR2 and are each composed of at least 7 exons. Pseudogenes of this gene are found on chromosomes 15, 18, and 21.
CAR is a transmembrane bound protein with two Ig-like extracellular domains, a transmembrane domain, and a cytoplasmic domain. The N-terminal segment comprises the two extracellular domains (D1 and D2). D1 is most distal from the membrane and contains a V/Ig-like fold whereas D2 is more proximal and
The protein is found to be expressed in various regions of the body including the heart, brain, and, more generally, epithelial cells. Moreover, CAR expression is not found in normal or tumour cell lines.
CAR is strongly expressed in the developing central nervous system where it is thought to mediate neurite outgrowth. In contrast,expression of CAR is undetectable in the adult nervous system. It functions as a homophilic and heterophilic cell adhesion molecule through its interactions with extracellular matrix glycoproteins such as: fibronectin, agrin, laminin-1 and tenascin-R. In addition, it is thought to regulate the cytoskeleton through interactions with actin and microtubules. Moreover, its cytoplasmic domain contains putative phosphorylation sites and a PDZ-interaction motif which suggests a scaffolding role.
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