Mistranslated protein in Escherichia coli.

Amino acid starvation of a variety of different types of cells has been reported to induce protein degradation and also specific mistranslation. For certain amino acid starvations, the mistranslated protein, which contains specific amino acid substitutions, can be separated and quantified by two-dimensional polyacrylamide gel electrophoresis. In this paper, I show that this specifically mistranslated protein, made during amino acid starvation, does not seem to be preferentially degraded during continued starvation or renewed growth. Specifically mistranslated ribosomal protein is also assembled into ribosomes in the same proportion that it is made. These results imply that the amino acid substitutions apparently made (lysine for asparagine or glutamine or histidine) do not lead to proteins recognized as grossly "abnormal" by the cell's proteolysis systems.