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Published May 24, 1985 | public
Journal Article

The "spliceosome": yeast pre-messenger RNA associates with a 40S complex in a splicing-dependent reaction

Abstract

The in vitro splicing reactions of pre-messenger RNA (pre-mRNA) in a yeast extract were analyzed by glycerol gradient centrifugation. Labeled pre-mRNA appears in a 40S peak only if the pre-mRNA undergoes the first of the two partial splicing reactions. RNA analysis after extraction of glycerol gradient fractions shows that lariat-form intermediates, molecules that occur only in mRNA splicing, are found almost exclusively in this 40S complex. Another reaction intermediate, cut 5' exon RNA, can also be found concentrated in this complex. The complex is stable even in 400 mM KCl, although at this salt concentration, it sediments at 35S and is clearly distinguishable from 40S ribosomal subunits. This complex, termed a "spliceosome," is thought to contain components necessary for mRNA splicing; its existence can explain how separated exons on pre-mRNA are brought into contact.

Additional Information

© 1985 American Association for the Advancement of Science. 2 February 1985; Accepted 14 April 1985. We thank Andrew Newman, who developed the yeast in vitro mRNA splicing system, for help and encouragement during the course of this work, as well as Soo-chen Cheng, R.-J. Lin, Gloria McFarland, Marge Fidler, and Joan Steitz for advice and critical discussion. Supported by a grant from NIH.

Additional details

Created:
August 19, 2023
Modified:
October 20, 2023