The termination of translation requires coordination between release factor proteins, the mRNA sequence, and ribosomes. Once a termination codon is read, release factors RF-1, RF-2, and RF-3 contribute to the hydrolysis of the growing polypeptide, which terminates the chain. Bases downstream the stop codon affect the activity of these release factors. In fact, some bases proximal to the stop codon suppress the efficiency of translation termination by reducing the enzymatic activity of the release factors. For instance, the termination efficiency of a UAAU stop codon is near 80% while the efficiency of UGAC as a termination signal is only 7%.