Translational Reinitiation: Reinitiation of lac Repressor Fragments at Three Internal Sites Early in the lac i gene of Escherichia coli*

摘要

Three early amber mutations in the lac i gene have been shown to arise from the codons corresponding to residues 7, 12, and 17 of the lac repressor polypeptide chain. All three mutations allow translational reinitiation at the same two sites, resulting in the synthesis of two lac repressor fragments. The amino-terminal sequences of these fragments show that the first site is the triplet coding for valine residue 23, while the second is the first internal in-phase AUG codon corresponding to residue 42.