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The 21‐kDa Polypeptide (VAP21) in the Rabies Virion Is a CD99‐Related Host Cell Protein
Author(s) -
Sagara Junji,
Tochikura Tadafumi S.,
Tanaka Hajime,
Baba Yoshihiro,
Tsukita Shoichiro,
Tsukita Sachiko,
Kawai Akihiko
Publication year - 1998
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1998.tb02285.x
Subject(s) - biology , complementary dna , microbiology and biotechnology , cdna library , antigen , peptide sequence , ectodomain , transmembrane protein , monoclonal antibody , antibody , virology , gene , biochemistry , genetics , receptor
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.