Translationally associated helix-destabilizing activity in rabbit reticulocyte lysate.

Helix-destabilizing activity associated with mRNA translation was detected in rabbit reticulocyte lysate by assessing the ability of the ribosome to read through mRNA/cDNA duplexes. Hybridization of globin mRNA to cDNA fragments which extend into the 5' nontranslated region fully block the translation of the hybridized message. However, hybridization of the mRNA to cDNA fragments which cover regions 3' to the initiation codon has no adverse effect on its translation. The translation of mRNA hybridized to this second category of cDNA fragments occurs without the total removal of cDNA. These results imply that the ribosomal complex, once fully assembled at the AUG initiation codon, can locally destabilize secondary structures as it moves along the message. This activity may be critical for translational elongation by the ribosome.