Journal of Cell Science 115, e1503-e1503 (2002)
© 2002 The Company of Biologists Limited
mRNA surveillance: nonsense-mediated and non-stop
Inaccurate transcription, RNA-processing errors and lymphocyte gene
rearrangements can all generate aberrant mRNAs whose translation would produce
dominant negative proteins that disrupt cell function. Cells must detect and
destroy such RNAs, but how do they discriminate them from normal mRNAs? In a
Commentary on p. 3033, Eileen
Wagner and Jens Lykke-Andersen discuss recent work that has identified two
mRNA surveillance mechanisms that do this: nonsense-mediated decay (NMD) and
non-stop decay. NMD destroys transcripts that contain premature termination
codons (PTCs). The last exon-exon junction is marked with an exon junction
complex (EJC), and, if a PTC is present upstream, a group of `Upf' proteins
triggers degradation of the mRNA during translation. Non-stop decay, by
contrast, targets RNAs that lack in-frame termination codons and does not
involve Upf proteins. Instead it requires the GTPase Ski7. Ski7 binds to the
empty A site in a ribosome that has reached the 3' end of an mRNA and
then recruits a multisubunit complex of exonucleases, termed the exosome, to
degrade the transcript.
Related articles in JCS:
- mRNA surveillance: the perfect persist
- Eileen Wagner and Jens Lykke-Andersen
JCS 2002 115: 3033-3038.
[Abstract]
[Full Text]
