Molecular Genetics

Aminoacyl tRNA availability may regulate completion of polypeptide synthesis.

Facts

• Fibroin is a 400K silk protein made by silk worms. When its mRNA is extracted and translated in a reticulocyte lysate system, discrete incomplete protein products are found. Addition of silk worm tRNA to the system causes the appearance of some full-length products.
• However, even with abundant silk worm tRNA addition, intermediate length products are still detected.
• The lengths of the products correlate with positions in the mRNA that adopt strong secondary structures.

Interpretations

• mRNA secondary structure can cause pausing in translation.
• In eukaryotes, termination may occur artefactually at translation pauses due to the absence of particular tRNAs.

Further information

• Though the potential of regulation of translation by the availability of particular tRNAs has been much discussed, there is little evidence supporting a role for such a mechanism in the regulation of gene expression.

This is page 2415 of Molecular Genetics by Ulrich Melcher, © 1997, 1998, 2000