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The poly(A)-binding protein facilitates in vitro translation of poly(A)-rich mRNA
M F Grossi de Sa1, N Standart, C Martins de Sa
1Institut Jacques Monod, Université Paris VII, France.
Abstract:
To investigate the role of the 73-kDa poly(A)-binding protein in protein synthesis, the effect of the addition of homo-polyribonucleotides on the translation of polyadenylated and non-adenylated mRNA was studied in the rabbit reticulocyte lysate. Poly(A) was found to be the most effective polynucleotide in inhibiting duck-globin mRNA translation, whereas it had no effect on the translation of polyribosomal duck-globin mRNP, or on the endogenous synthesis of the rabbit reticulocyte lysate. The translation of poly(A)-free mRNA was not affected by the addition of poly(A). Furthermore, we found that the inhibiting effect of poly(A) can be reversed by addition of purified poly(A)-binding protein. It is thus likely that the 73-kDa poly(A)-binding protein is an essential factor necessary for poly(A)-rich mRNA translation.
Insights
The 73-kDa poly(A)-binding protein is essential for translating poly(A)-rich messenger RNA (mRNA). Adding poly(A) inhibits translation, but this effect is reversed by the protein, confirming its role in protein synthesis.
Area of Science:
- Molecular Biology
- Biochemistry
- Gene Expression
Background:
- Polyadenylation is a crucial post-transcriptional modification of eukaryotic messenger RNA (mRNA).
- The poly(A) tail's role in mRNA stability and translation is well-established, but the specific function of poly(A)-binding proteins remains under investigation.
- The 73-kDa poly(A)-binding protein (PABP) is a key component involved in mRNA processing and translation.
Purpose of the Study:
- To elucidate the specific role of the 73-kDa poly(A)-binding protein in the process of protein synthesis.
- To determine the impact of poly(A) homopolyribonucleotides on the translation of both polyadenylated and non-adenylated mRNA.
Main Methods:
- Utilized a rabbit reticulocyte lysate system for in vitro translation assays.
- Investigated the effects of adding various homo-polyribonucleotides, particularly poly(A), on mRNA translation.
- Assessed the influence of purified poly(A)-binding protein on poly(A)-mediated inhibition.
Main Results:
- Poly(A) was the most potent inhibitor of duck-globin mRNA translation.
- Poly(A) did not affect the translation of polyribosomal duck-globin messenger ribonucleoprotein complexes (mRNP) or endogenous lysate synthesis.
- The inhibitory effect of poly(A) on translation was reversed upon the addition of purified 73-kDa poly(A)-binding protein.
- Translation of poly(A)-free mRNA remained unaffected by poly(A) addition.
Conclusions:
- The 73-kDa poly(A)-binding protein is likely an essential factor required for the translation of poly(A)-rich mRNA.
- These findings highlight the critical role of PABP in regulating gene expression at the translational level.