title: Identification and characterization of a 30K protein (Ad4E3-30K) encoded by the E3 region of human adenovirus type 4.
abstract: Human adenovirus type 4 (Ad4), the sole member of subgroup E, contains an open reading frame in the E3 region predicted to encode a unique 30-kDa protein (named Ad4E3-30K). Ad4E3-30K is predicted to be an integral membrane protein containing an N-terminal signal sequence, a lumenal domain, a transmembrane domain near the C-terminus, and a 37-amino-acid cytoplasmic tail. To determine whether this protein is expressed, rabbit polyclonal antisera were raised against 30K-containing fusion proteins expressed in bacteria. A 30K protein was detected by immunoprecipitation from cell-free translation products and from Ad4-infected A549 cells radiolabeled in the presence of tunicamycin. The protein was detected at only low levels in infected cells. It was not synthesized by a mutant with a large E3 deletion that includes the Ad4E3-30K gene. This mutant grows as well as wild-type Ad4 in culture. Features of Ad4E3-30K were characterized in different transient expression systems. The protein underwent glycosylation by addition of approximately six asparagine-linked oligosaccharides. These glycans were sensitive to endoglycosidase H, indicating that they were either high-mannose or hybrid types, but not complex types, and that the protein did not pass through the Golgi apparatus. Immunofluorescence staining of transfected cells revealed that Ad4E3-30K was localized primarily in the endoplasmic reticulum and nuclear envelope.
authors.affiliation: Department of Molecular Microbiology and Immunology, St. Louis University School of Medicine, 1402 South Grand Boulevard, St. Louis, Missouri, 63104, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: W S
authors.initials: WS
authors.lastname: Wold
mesh_terms: D017503:Adenovirus E3 Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D000260:Adenoviruses, Human / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D006031:Glycosylation; D006596:Hexosaminidases / Q000378:metabolism; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D013997:Time Factors; D014162:Transfection; D014616:Vaccinia virus / Q000502:physiology
chemical_list: D017503:Adenovirus E3 Proteins; D007106:Immune Sera; D006596:Hexosaminidases