Ochre Suppressor (Molecular Biology)

Ochre suppressors are mutant tRNAs that translate the UAA (ochre) termination codon as a sense codon. Ochre suppressors allow for protein synthesis beyond the translational block resulting in active protein. Due to wobble decoding, most ochre suppressors also decode the UAG (amber) stop codon. Ochre mutations cause protein synthesis to terminate prematurely, resulting in inactive, truncated polypeptides. Hence the term "suppressor;" these mutant tRNAs "suppress" the phenotypes of ochre mutations. These suppressors have been extensively used in prokaryotic genetic studies, and in studies of the translational apparatus and mechanisms. For complete discussions of these and other suppressors, see Nonsense Suppression, Suppressor tRNA, and Genetic Suppression.