Biochemistry

Safe Passage

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Science  15 Aug 2003:
Vol. 301, Issue 5635, pp. 897
DOI: 10.1126/science.301.5635.897b

A variety of RNA processing events can occur after RNA is made from DNA (transcription) and before it is used to make protein (translation). Two such processes are RNA editing and nonsense-mediated decay (NMD). Editing enzymes (for the role of editing in innate immunity, see KewalRamani and Coffin, Perspectives, this issue, p. 923) can convert adenosine to inosine in the messenger RNAs (mRNAs) of ion channels and neurotransmitter receptors or, in a similar fashion, cytosine to uridine. The latter reaction is carried out in the nuclear compartment by a protein complex that includes apolipoprotein B mRNA editing catalytic polypeptide 1 (APOBEC1) as well as APOBEC1 complementation factor (ACF). Changing C6666 to a U introduces a termination codon and results in the synthesis of the shortened apoB 48 isoform rather than the apoB 100 protein. Chester et al. show that the APOBEC1-ACF editing complex accompanies the already-edited mRNA into the cytoplasm and protects it from degradation via NMD, which normally acts as a surveillance system to prevent the translation of mRNAs that contain premature termination codons, a source of deleterious mutant proteins. — GJC

EMBO J. 22, 3971 (2003).

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