Molecular Biology

Benefits of Careful Editing

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Science  01 Sep 2000:
Vol. 289, Issue 5484, pp. 1433
DOI: 10.1126/science.289.5484.1433d

In eukaryotes, the faithful copying of DNA sequences into RNA transcripts does not in itself ensure that an organism can produce the diverse array of proteins it needs. The initial RNA transcripts, called precursor messenger RNAs (pre-mRNAs), experience a series of tightly regulated processing events, such as the splicing reactions that remove nocoding sequences, or introns. An additional, less common form of pre-mRNA processing is called RNA editing. In one type of editing, adenosine (A) is converted to inosine (I) by an enzyme called ADAR (for adenosine deaminase acting on RNA). In the case of the pre-mRNAs encoding glutamate receptor subunits, this editing is site-specific and results in a mixture of functionally distinct proteins that differ by only one amino acid.

To examine the biological significance of RNA editing, Palladino et al. generated strains of the fruit fly Drosophila that lacked a functional ADAR gene and therefore were incapable of A-to-I editing. Although the flies developed normally, the adults showed profound behavioral defects in motor control, mating, and flight. These deficits increased in severity with age and were associated with neurodegeneration. Thus, RNA editing has a critical role in nervous system function, perhaps as a post-transcriptional means of generating subtle yet functional variation. — PAK

Cell102, 437 (2000).

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