Fig. 2.

STOP codon read-through. High translation fidelity ensures STOP codon recognition as such by the release factor complex according to the canonical termination mechanism (left). However, non Watson–Crick base pairing between the UAG codon and a tRNA containing a near cognate anticodon could lead to the incorporation of a new amino acid (green) instead of translation termination, allowing for the synthesis of longer polypeptides containing a C-terminal extension (right). This phenomenon known as STOP codon read-through, although infrequent, occurs at basal levels under normal conditions, and several works point to the possibility that it could be a physiological mechanism of translation regulation. Ongoing research is focused on the elucidation of the impact that the incorporation of C-terminal additional domains by STOP codon read-through could have on cell physiology