title: naf, a trans-regulating negative-acting factor encoded within the mouse mammary tumor virus open reading frame region.
abstract: The mouse mammary tumor virus (MMTV) long terminal repeat (LTR) open reading frame (ORF) encodes a negative acting factor (naf). In our test system, naf mediates its effect in trans on another MMTV provirus in which the 5' LTR has been replaced by that of Rous sarcoma virus. naf effects are evidenced at the level of transcriptional initiation rather than as reduced mRNA stability. The introduction of a premature termination codon into the MMTV LTR-encoded ORF abolishes the transcriptional down regulation localizing naf within the ORF. In addition, sequences in the gag/pol genes between +320 and +646 and between +3626 and +4590 relative to the site of transcription initiation are also involved in the MMTV-mediated transcriptional down regulation.
authors.affiliation: GSF-München, Abteilung für Molekulare Zellpathologie, Neuherberg, Federal Republic of Germany.
authors.forename: B
authors.initials: B
authors.lastname: Salmons
authors.forename: V
authors.initials: V
authors.lastname: Erfle
authors.forename: G
authors.initials: G
authors.lastname: Brem
authors.forename: W H
authors.initials: WH
authors.lastname: Günzburg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D015967:Gene Expression Regulation, Viral; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011533:Proviruses / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D012333:RNA, Messenger