FIG. 18.

Polysome disruption as a key process in mRNA degradation. An integrated scheme of mRNA decay events in yeast is shown. Triggering events are generally likely to disrupt the mRNP and polysome structure, which may therefore constitute the common intermediate step leading to further decay events. Since mRNA interacts with both nuclear and cytoplasmic proteins on its pathway through the nucleus into the cytoplasm, the interactions with both groups of proteins may be relevant to the control of mRNA degradation. Further research is expected to reveal whether this mechanism or more specific coupling mechanisms underlie decay pathways.