title: [Turnover of nuclear RNA. II. Conveyer model of synthesis and maturation of nuclear RNA as an alternative for a stochastic model].
abstract: It is shown that the stochastic model of hnRNA decay is inconsistent with a number of experimental data. The model of ordered in time and space movement of nascent and post-transcriptional RNA molecules "on conveyer" coupled with certain processing steps is put forward. Since degradation of the pre-mRNA molecule proceeds not instantaneously but in several subsequent steps, the notion of the "exiton" is introduced. The exiton is proposed to be a submolecular metabolically indivisible fragment of RNA molecule which decays as a unit. From this point of view, a population of nuclear RNAs, as a whole, can be presented (and easily mathematically treated) as a community of exiton transporters of various life spans moving in parallel. The life-time spectrum of exitons in population of rat liver hnRNA was computed. The share of exitons with life-time from 41.5 to 42.5 min appeared to be most in the population. Exitons with life-times above 1 h and 2 h comprise approximately 50 and 20% of the total population, respectively. The consequences of the model proposed are discussed.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D007700:Kinetics; D008433:Mathematics; D008957:Models, Genetic; D012332:RNA, Heterogeneous Nuclear / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D012332:RNA, Heterogeneous Nuclear
vernacular_title: Obmen iadernykh RNK. II. Konveĭernaia model' sinteza i sozrevaniia iadernykh RNK kak al'ternativa stokhasticheskoĭ modeli.