title: Internal initiation of translation on the vesicular stomatitis virus phosphoprotein mRNA yields a second protein.
abstract: In vitro translation of a mixture of the vesicular stomatitis virus (VSV) polyadenylated mRNAs yielded a previously undetected protein with a molecular weight of approximately 7,000 (7K protein). Hybrid-arrested translation demonstrated that both the 7K protein and the VSV phosphoprotein (P protein) were encoded by the P protein message. Immunoprecipitation of the 7K protein with monoclonal antiserum directed against the P protein indicated that the two products were encoded in the same open reading frame. A protein of approximately the same size was immunoprecipitated from cytoplasmic extracts of VSV-infected cells by both the polyclonal and monoclonal antisera, and it is likely that it was a previously unrecognized viral gene product. Translational mapping of the P protein mRNA in vitro indicated that the 7K protein was encoded in the 3' one-third of the sequence. The synthesis of the 7K protein in vitro was unaffected by hybrid arrest conditions which blocked the 5' two-thirds of the mRNA and inhibited synthesis of the P protein. These results imply that the ribosomes bind and initiate translation internally on the P protein mRNA at a site located hundreds of nucleotides downstream from the capped 5' end.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001483:Base Sequence; D002460:Cell Line; D003062:Codon; D006224:Cricetinae; D005822:Genetic Vectors; D008970:Molecular Weight; D010750:Phosphoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D013997:Time Factors; D014721:Vesicular stomatitis Indiana virus / Q000378:metabolism*; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins / Q000032:analysis / Q000096:biosynthesis*
chemical_list: D000911:Antibodies, Monoclonal; D003062:Codon; D010750:Phosphoproteins; D012333:RNA, Messenger; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins