- Termination of translation is signalled by stop codons (UAG, UAA and UGA, in most organisms).
- Translation is terminated by hydrolysis of the polypeptidyl-tRNA
linkage with concomittant release of mRNA and ribosomal subunits.
- Stop codons are sufficient for termination. Yet, they can be made
more efficient by trans-acting factors.
- Mutation of sense codons to nonsense codons (stop codons) results
in synthesis of a truncated polypeptide. In polycistronic mRNAs,
these mutations affect expression of downstream cistrons. The premature termination events can be suppressed by second-site mutations.
- In eukaryotes, nonsense mutations can lead to destruction of the mRNA by a process called NMD.
- Termination suppression is a natural mechanism in the synthesis of some polypeptides.
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This is page 242 of Molecular Genetics by Ulrich Melcher, © 1997, 1998, 2001
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