The Sound of a Silent Mutation

Another dogma in cell biology seems about to be toppled: If a mutation in a gene doesn't change the basic sequence of building blocks, then it has no effect. Chava Kimchi-Sarfaty of the U.S. Food and Drug Administration in Bethesda, Maryland, and colleagues report online this week in Science that such "silent mutations" can, under certain circumstances, determine how well a final protein performs--an "extremely provocative" result, says cell biologist William Skach of Oregon Health & Science University in Portland. Silent mutations occur when the change of a single DNA nucleotide within a protein-coding portion of a gene does not affect the sequence of amino acids that make up the gene's protein. That's possible because proteins are encoded by "triplets" of nucleotides, each responsible for adding a particular amino acid to the protein chain. A change in one nucleotide, however, doesn't always change the triplet's meaning; the mutated triplet may still add the same amino acid. And when the amino acids of a protein stay the same, researchers believed, so do its structure and function. full story on "www.sciencemag.org":[ http://sciencenow.sciencemag.org/cgi/content/full/2006/1222/2]

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