Journal of Cell Science 115, e2001-e2001 (2002)
Copyright © 2002 The Company of Biologists Limited
doi:
Co-transcriptional RNA processing: coincidence or coupling?
Numerous studies have shown that pre-mRNA processing 5'
capping, splicing and polyadenylation takes place while the mRNA is
being transcribed. Does this simply reflect the fact that these reactions get
going before the polymerase (Pol II) has had time to transcribe the entire
gene, or are the processes functionally coupled? In a Commentary on
p. 3865, Karla Neugebauer
reviews the evidence for functional coupling. Capping enzymes and components
of the polyadenylation machinery bind directly to Pol II, and there is good
evidence for coupling in these cases. Pol II has also been proposed to recruit
splicing factors, but Neugebauer argues that any transcription-splicing
coupling is more likely to involve interactions between splicing snRNPs and
elongation factors; moreover, she notes that the recursive splicing of
transcripts such as the Drosophila Ubx pre-mRNA rules out a strict
coupling of splice site synthesis and binding of splicing factors to these
transcripts. Finally, Neugebauer points out that mRNA processing is also
functionally coupled to mRNA export, since improperly processed mRNAs are
often retained at transcription units, which are known to recruit export
factors.

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Related articles in JCS:
- On the importance of being co-transcriptional
- Karla M. Neugebauer
JCS 2002 115: 3865-3871.
[Abstract]
[Full Text]