title: Env and Vpu proteins of human immunodeficiency virus type 1 are produced from multiple bicistronic mRNAs.
abstract: Three size classes of human immunodeficiency virus type 1 (HIV-1) mRNAs are produced in infected cells: full-length, intermediate, and small. Here we report that the intermediate-size class of viral mRNAs is heterogeneous, consisting of at least 12 differentially spliced species. This group contains nine bicistronic mRNAs producing Env and Vpu and three mRNAs expressing only the first exon of tat. In the latter mRNAs, Env and Vpu expression is blocked by the presence of the upstream tat open reading frame. We conclude that internal initiation of translation is not the mechanism for generation of the bicistronic env mRNAs. Translation of HIV-1 mRNAs is consistent with the scanning mechanism in which Env is produced by leaky scanning from mRNAs that contain env as the second or third reading frame. Env and Vpu proteins are expressed from the same mRNAs and are coordinately regulated by Rev. This arrangement may reflect a requirement for coordinate expression of Vpu and Env.
authors.affiliation: Basic Research Program, National Cancer Institute-Frederick Cancer Research and Development Center, Maryland 21702-1201.
authors.forename: S
authors.initials: S
authors.lastname: Schwartz
authors.forename: B K
authors.initials: BK
authors.lastname: Felber
authors.forename: E M
authors.initials: EM
authors.lastname: Fenyö
authors.forename: G N
authors.initials: GN
authors.lastname: Pavlakis
mesh_terms: D001483:Base Sequence; D015967:Gene Expression Regulation, Viral; D015686:Gene Products, env / Q000235:genetics*; D015696:Gene Products, tat / Q000235:genetics; D015752:Genes, env / Q000235:genetics*; D015497:HIV-1 / Q000235:genetics*; D054298:Human Immunodeficiency Virus Proteins; D008969:Molecular Sequence Data; D010442:Peptide Chain Initiation, Translational; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics*; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics*; D054322:tat Gene Products, Human Immunodeficiency Virus; D000086082:Viroporin Proteins
chemical_list: D015686:Gene Products, env; D015696:Gene Products, tat; D054298:Human Immunodeficiency Virus Proteins; D012333:RNA, Messenger; D012367:RNA, Viral; D054334:Viral Regulatory and Accessory Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins