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[Interrelationship between protein synthesis and mRNA metabolism in rat liver cells]
Abstract:
It is demonstrated that RNA isolated from polyribosomes and postmitochondrial fraction of rat liver cells and bound to nitrocellulose filters (Milliport) represent mRNA. RNA taken from the nitrocellulose filters sedimented in sucrose concentration gradient with a wide peak within the range of 18--6S, attaining a maximum at 12S. The (A+U)/(G+C) ratio of this RNA was equal to 1.04. On the other hand, the same ratio for rRNA was 0.64. Specific radioactivity of polysomal mRNA containing poly-A sequences, was significantly lower at 14-hour labelling with 14C-orotate than at 4-hour labelling (control). Inhibitors (cycloheximide, puromycin, ethionine, actinomycin D) stabilized polysomal mRNA. Specific radioactivity of postmitochondrial fraction mRNA was higher at 14-hour labelling than at 4-hour labelling. Specific radioactivity of postmitochondrial fraction mRNA during protein synthesis blocking by different inhibitors was comparable to those of control animals. It is hypothesized that active translation is necessary for the initiation of rat liver mRNA degradation.
Insights
Rat liver messenger RNA (mRNA) degradation appears to require active translation. Inhibitors of protein synthesis stabilized polysomal mRNA, suggesting translation initiation is key for mRNA decay.
Area of Science:
- Molecular Biology
- Biochemistry
Context:
- Messenger RNA (mRNA) plays a crucial role in protein synthesis, and its stability is tightly regulated.
- Understanding mRNA degradation pathways is essential for controlling gene expression.
Purpose:
- To investigate the factors influencing messenger RNA (mRNA) degradation in rat liver cells.
- To determine the role of active translation in the initiation of mRNA decay.
Summary:
- Messenger RNA (mRNA) isolated from rat liver polyribosomes and postmitochondrial fractions was identified and characterized.
- Specific radioactivity measurements indicated that polysomal mRNA stability is enhanced by protein synthesis inhibitors, suggesting active translation is necessary for mRNA degradation initiation.
- The (A+U)/(G+C) ratio of mRNA was found to be 1.04, distinct from ribosomal RNA (rRNA).
Impact:
- This study provides a hypothesis that active translation is a prerequisite for the initiation of rat liver mRNA degradation.
- Findings contribute to a deeper understanding of post-transcriptional gene regulation and mRNA turnover mechanisms.