title: The 21-kDa polypeptide (VAP21) in the rabies virion is a CD99-related host cell protein.
abstract: In our monoclonal antibody (MAb) stocks prepared against the BHK-21 cell antigens, two (#11875 and 28276) recognized a 21-kDa polypeptide (referred to as VAP21) which is efficiently incorporated into the rabies virion. By using these MAbs, we isolated the cDNA clones that encoded a polypeptide of 144 amino acids from our BHK-21 cell cDNA library. Based on the following evidence, the cDNA was assumed to encode a full-length sequence of VAP21 antigen: i) expression of the cDNA in animal cells resulted in the production of a polypeptide recognized by the two MAbs, and its electrophoretic mobility was the same as that of authentic VAP21 antigen; and ii) immunization with the products from the cDNA-transformed E. coli cells raised specific antibodies in rabbits that recognized a 21-kDa polypeptide in the virion. From the deduced amino acid sequence, it is suggested that the VAP21 antigen has a molecular structure of type-I transmembrane protein containing characteristic proline-rich and glycine-rich regions in its ectodomain. Homology searches resulted in finding homologous sequences (totally about 40% homology) in the human MIC2 gene product (CD99; 32-kDa) of T lymphocytes. These results suggest that the VAP21 antigen in the rabies virion is a cellular CD99-related transmembrane protein.
authors.affiliation: Department of Molecular Microbiology, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Sagara
authors.forename: T S
authors.initials: TS
authors.lastname: Tochikura
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
authors.forename: Y
authors.initials: Y
authors.lastname: Baba
authors.forename: S
authors.initials: S
authors.lastname: Tsukita
authors.forename: S
authors.initials: S
authors.lastname: Tsukita
authors.forename: A
authors.initials: A
authors.lastname: Kawai
mesh_terms: D000071443:12E7 Antigen; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000737:chemistry* / Q000235:genetics; D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000737:chemistry* / Q000235:genetics; D002460:Cell Line; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D011820:Rabies virus / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014764:Viral Proteins; D014771:Virion / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D000071443:12E7 Antigen; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules; D018076:DNA, Complementary; D008565:Membrane Proteins; C113732:VAP21 protein, Rabies virus; D014764:Viral Proteins