Such RNA molecules interact with a downstream region to form a pseudoknot structure; the region varies according to the virus but pseudoknot formation is known to stimulate frameshifting.

In the classical situation, a sequence 32 nucleotides downstream of the stem is complementary to part of the loop.

During protein synthesis, rapidly changing conditions in the cell can cause ribosomal pausing.

In coronaviruses, this can affect growth rate and trigger translational abandonment.

This releases the ribosome from the mRNA and the incomplete polypeptide is targeted for destruction.