Stop codons are used to signal the ribosome to terminate the decoding of an mRNA 
template. Recent studies on translation termination in the yeast Saccharomyces 
cerevisiae have not only enabled the identification of the key components of the 
termination machinery, but have also revealed several regulatory mechanisms that 
might enable the controlled synthesis of C-terminally extended polypeptides via 
stop-codon readthrough. These include both genetic and epigenetic mechanisms. 
Rather than being a translation 'error', stop-codon readthrough can have 
important effects on other cellular processes such as mRNA degradation and, in 
some cases, can confer a beneficial phenotype to the cell.