A mammalian activity required for the second step of pre-messenger RNA splicing

Laura A. Lindsey, Allen J. Crow, Mariano A. Garcia-Blanco

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Splicing of precursors to messenger RNAs occurs via a two-step mechanism. In the first step, the 5'-exon is released concomitant with the production of a lariat intermediate, and in the second step, the exons are joined, releasing the intron in the form of a lariat product. Several gene products of the yeast Saccharomyces cerevisiae have been shown to be required exclusively for the second step. Although mammalian proteins have been implicated in the second step of splicing, none have been shown to act only at this step. We identify here the first mammalian activity shown to be exclusively required for the second step. The activity was shown to increase by 5-fold the rate for this splicing step, whereas it had no effect on the rate of the first step. The activity was not affected by treatment with micrococcal nuclease, whereas it is sensitive to heating to 55 °C, suggesting that it is not dependent on an RNA, but more likely is a protein. The second step activity was separated from other factors required for the first step and from PSF, a splicing factor thought to have a second step activity. The activity does not require ATP hydrolysis, suggesting that it acts at a late stage of the second step of splicing.

Original languageEnglish (US)
Pages (from-to)13415-13421
Number of pages7
JournalJournal of Biological Chemistry
Issue number22
StatePublished - Jun 2 1995
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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