Changing genetic information through RNA editing. Bioessays

RNA editing, the post-transcriptional alteration of a gene-encoded sequence, is a widespread phenomenon in eukaryotes. As a consequence of RNA editing, functionally distinct proteins can be produced from a single gene. The molecular mechanisms involved in-clude single or multiple base insertions or deletions as well as base substitutions. In mammals, one type of substitutional RNA editing, characterized by site-speci-fic base-modification, was shown to modulate important physiological processes. The underlying reaction me-chanism of substitutional RNA editing involves hydro-lytic deamination of cytosine or adenosine bases to uracil or inosine, respectively. Protein factors have been characterized that are able to induce RNA editing in vitro. A supergene family of RNA-dependent deami-nases has emerged with the recent addition of adeno-sine deaminases specific for tRNA. Here we review the developments that have substantially increased our understanding of base-modification RNA editing over the past few years, with an emphasis on mechanistic differences, evolutionary aspects and the first insights into the regulation of editing activity. BioEssay