Molecular functions of nuclear actin in transcription.
Actin is not only a major cytoskeletal component in all eukaryotic cells but also a nuclear protein that plays a role in gene transcription. We put together data from in vitro and in vivo experiments that begin to provide insights into the molecular mechanisms by which actin functions in transcription. Recent studies performed in vitro have suggested that actin, in direct contact with the transcription apparatus, is required in an early step of transcription that is common to all three eukaryotic RNA polymerases. In addition, there is evidence from in vivo studies that actin is involved in the transcription elongation of class II genes. In this case, actin is bound to a specific subset of premessenger RNA binding proteins, and the actin-messenger RNP complex may constitute a molecular platform for recruitment of histone-modifying enzymes. We discuss a general model for actin in RNA polymerase II transcription whereby actin works as a conformational switch in conjunction with specific adaptors to facilitate the remodeling of large macromolecular assemblies at the promoter and along the active gene.
Department of Cell and Molecular Biology, Karolinska Institutet, SE-117 77 Stockholm, Sweden. piergiorgio.percipalle@ki.se
Piergiorgio
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Percipalle
Neus
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Visa
D000199:Actins / Q000502:physiology*; D000205:Actomyosin / Q000502:physiology; D000818:Animals; D042002:Chromatin Assembly and Disassembly / Q000502:physiology; D051548:Histone Acetyltransferases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D019476:Insect Proteins / Q000502:physiology; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000502:physiology; D009218:Myosins / Q000502:physiology; D009687:Nuclear Proteins / Q000502:physiology*; D012335:RNA, Ribosomal / Q000096:biosynthesis; D016601:RNA-Binding Proteins; D014158:Transcription, Genetic
D000199:Actins; D006657:Histones; D019476:Insect Proteins; D020409:Molecular Motor Proteins; D009687:Nuclear Proteins; D012335:RNA, Ribosomal; D016601:RNA-Binding Proteins; C404122:hrp65 protein, Chironomus tentans; D000205:Actomyosin; D051548:Histone Acetyltransferases; D009218:Myosins