The stop signal controls the efficiency of release factor-mediated translational termination.

Abstract

There are three important steps in protein synthesis where signals in the mRNA are critical for a successful outcome, namely the production of a functional protein. First the information in the nucleic acid which is to be translated into an amino acid sequence is signalled by successive triplet sense codons, second the frame is set by one sense codon, the initiation codon, which acts as the start of translation of the encoded information, and third the end of the information frame also has to be marked by a specific signal. The use of a range of different signals to mark each of these steps allows for differences in the efficiency with which different proteins are produced. In this review the focus is on the signal that marks the end of the frame, the translational termination signal. For a long time it was thought that termination would be the least interesting phase of protein synthesis but it has subsequently been found to have unexpected dimensions, providing a substratum of cellular regulation. The translational stop signal should now be thought of as a full stop in the large majority of cases, but as a pause in a fundamentally important minority of cases where alternative genetic events can occur.