Abstract: The invention provides isolated nucleic acid molecules which encode a coxsackievirus and adenovirus receptor protein, CAR. The invention also provides antisense nucleic acid molecules, recombinant expression vectors containing CAR nucleic acid molecules, host cells into which the expression vectors have been introduced, and nonhuman transgenic animals in which a CAR gene has been introduced or disrupted. The invention still further provides isolated CAR proteins, fusion proteins, antigenic peptides and anti-CAR antibodies. Diagnostic, screening, and therapeutic methods utilizing compositions of the invention are also provided.