Letter | Published:

Mutation blocking the specific degradation of reinitiation polypeptides in E. coli

Naturevolume 257pages329331 (1975) | Download Citation



A NONSENSE mutation in a bacterial gene leads to the synthesis of two kinds of incomplete polypeptides1–4. These are the termination, or T, fragments extending from the normal N terminus to the site of mutation, and the reinitiation, or R, fragments initiating distal to the end of the T fragment and continuing to the normal C terminus. Both the T and the R fragments produced by nonsense mutations in the β-galactosidase gene of Escherichia coli (z gene) are rapidly and selectively degraded in vivo5–7. This contrasts strongly with the wild-type β-galactosidase, which is stable5,7. The degradation of mutant polypeptides implies the existence of proteolytic systems which can distinguish these unstable proteins from the stable ones.

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  1. Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 11724

    • B. N. APTE


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