A mutation in which a polypeptide chain is terminated prematurely. Amber mutations are the result of a base substitution that converts a codon specifying an amino acid into UAG, which signals chain termination. In certain strains of E. coli amber mutations are suppressed. These strains contain a tRNA with an AUC anticodon, which inserts an amino acid at the UAG site and hence permits translation to continue. See ochre mutation, nonsense mutation.
Subjects: Genetics and Genomics — Chemistry.