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Ribonucleotide sequences non-adjacent to poly(A) participate in the poly(A)-protein complex in 15S duck globin mRNP
Abstract:
The study of the interaction between mRNA and proteins in the polyribosomal 15 S duck globin messenger ribonucleoprotein complex showed that proteins protect specific mRNA sequences against digestion by the nonspecific micrococcal nuclease (Nucleic Acids Research 6 (8) 2787, 1979). Here we report the isolation of the poly(A)-protein RNP complex from nuclease digested 15 S mRNP by two different methods: sucrose gradient sedimentation and oligo(dT)-cellulose chromatography. We show by fingerprint analysis, that aprt from the periodically fragmented poly(A) segment, mRNA sequences adjacent and non-adjacent to the poly(A) segment are protected by the poly(A) binding proteins against nuclease digestion. The duck globin poly(A)-protein RNP complex, with a sedimentation coefficient between 7 S and 10 S, shows a characteristic protein composition, with a major 73,000 MW polypeptide and some minor components. The results are discussed in view of a dynamic ribonucleoprotein structure.
Insights
Proteins bound to messenger RNA (mRNA) protect specific sequences, including those near the poly(A) tail, from nuclease digestion. This reveals a dynamic ribonucleoprotein structure involved in mRNA regulation.
Area of Science:
- Molecular Biology
- Biochemistry
- RNA Biology
Background:
- Proteins interact with messenger RNA (mRNA) within ribonucleoprotein (RNP) complexes.
- Previous studies indicated that proteins shield specific mRNA sequences from nuclease activity.
Purpose of the Study:
- To isolate and characterize the poly(A)-protein RNP complex from nuclease-digested duck globin 15 S mRNP.
- To investigate the role of poly(A)-binding proteins in protecting mRNA sequences from nuclease digestion.
Main Methods:
- Isolation of the poly(A)-protein RNP complex using sucrose gradient sedimentation and oligo(dT)-cellulose chromatography.
- Fingerprint analysis to identify protected mRNA sequences.
- Characterization of the protein composition of the RNP complex.
Main Results:
- The poly(A)-protein RNP complex was successfully isolated.
- mRNA sequences adjacent and non-adjacent to the poly(A) segment were protected by poly(A)-binding proteins.
- The complex exhibited a distinct protein profile, featuring a prominent 73,000 MW polypeptide.
Conclusions:
- Poly(A)-binding proteins play a crucial role in protecting mRNA from nuclease degradation.
- These findings support a model of dynamic ribonucleoprotein structure influencing mRNA stability and accessibility.