RNA editing

RNA editing is a co- or post-transcriptional process in which select nucleotide sequences in RNA are altered from that originally encoded in the genome. Double-stranded RNA-specific adenosine deaminases convert adenosine residues to inosine in messenger RNA precursors (pre-mRNA). Their main physiological substrates are pre-mRNAs. Extensive analysis of cDNAs from 5-HT2C receptor reveals post-transcriptional modifications indicative of adenosine-to-inosine RNA editing (Burns et al. 1997). RNA transcripts encoding the 5-HT2c receptor undergo adenosine-to-inosine RNA editing events at up to five specific sites. Interestingly, reduced G protein-coupling efficiency for the edited isoforms is primarily due to silencing of the constitutive activity of the non-edited 5-HT2c receptor (Niswender et al. 1999). No further example of modified GPCR functions by mRNA editing has been reported yet.

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