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A direct evidence for the involvement of poly(A) in protein synthesis
Abstract:
A radioactive polyadenylated globin mRNA was translated in either rabbit reticulocyte lysate or wheat germ extract under various conditions. When globin mRNA was translated, globin synthesis was directly proportional to the rate of loss in A units from the poly(A) tail. On the other hand, when globin poly(A) mRNA was incubated under non-translated conditions, no loss of A units was detected. The presence of ribonuclease inhibitor in the reaction mixture did not alter either the rate of globin synthesis or the loss in A units from the poly(A) tail. The present data suggests a correlation between protein synthesis and loss in A units from the poly(A) tail.
Insights
Protein synthesis from globin mRNA correlates with the shortening of its poly(A) tail. This poly(A) tail shortening, or deadenylation, occurs during translation but not when the mRNA is idle.
Area of Science:
- Molecular Biology
- Gene Expression
- RNA Metabolism
Background:
- The poly(A) tail of messenger RNA (mRNA) plays a crucial role in mRNA stability and translation efficiency.
- Deadenylation, the shortening of the poly(A) tail, is a key step in mRNA decay and translational control.
- The precise relationship between active protein synthesis and poly(A) tail shortening in eukaryotic systems remains an area of investigation.
Purpose of the Study:
- To investigate the relationship between globin synthesis and poly(A) tail shortening in vitro.
- To determine if active translation is required for poly(A) tail deadenylation.
- To assess the role of ribonuclease inhibitors in modulating these processes.
Main Methods:
- Translation of radioactive polyadenylated globin mRNA in rabbit reticulocyte lysate and wheat germ extract.
- Monitoring globin synthesis via radioactivity detection.
- Quantifying poly(A) tail length by measuring the loss of 'A' units.
- Incubation under both translated and non-translated conditions.
- Inclusion of ribonuclease inhibitors in reaction mixtures.
Main Results:
- Globin synthesis was directly proportional to the rate of poly(A) tail shortening during translation.
- No significant loss of 'A' units from the poly(A) tail was observed when mRNA was incubated under non-translated conditions.
- The addition of ribonuclease inhibitor did not affect the rate of globin synthesis or poly(A) tail shortening.
Conclusions:
- The data strongly suggest a direct correlation between active protein synthesis and the progressive shortening of the poly(A) tail.
- Poly(A) tail deadenylation appears to be coupled with the translation process.
- These findings contribute to understanding the post-transcriptional regulation of gene expression.