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Updated: May 7, 2026
08:53
A Reporter Based Cellular Assay for Monitoring Splicing Efficiency
Published on: September 15, 2021
Alternative spliceosome assembly pathways revealed by single-molecule fluorescence microscopy
Inna Shcherbakova1, Aaron A Hoskins, Larry J Friedman
1Department of Biochemistry and Molecular Pharmacology, Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA; Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA.
Cell Reports
|October 1, 2013
Summary
Spliceosome assembly in yeast can occur through two distinct pathways: U1-first or U2-first. Both pathways lead to functional spliceosomes, indicating flexibility in gene expression. This finding impacts our understanding of spliceosome assembly mechanisms.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Spliceosome-mediated intron removal is crucial for eukaryotic gene expression.
- Previous models proposed a strictly ordered, U1-snRNP-first pathway for yeast spliceosome assembly.
Purpose of the Study:
- To investigate the initial steps of spliceosome assembly in yeast.
- To determine if alternative assembly pathways exist beyond the U1-first model.
Main Methods:
- Colocalization single-molecule spectroscopy was employed.
- Initial spliceosome assembly was monitored on eight different Saccharomyces cerevisiae pre-mRNAs.
Main Results:
- Active yeast spliceosomes can assemble via both U1-first and U2-first pathways.
- Both pathways produce functionally equivalent prespliceosomes.
- Both pathways are operational on all studied introns, with varying flux.
Conclusions:
- Multiple pathways exist for functional spliceosome assembly in yeast.
- These findings challenge the exclusively ordered model and offer insights into spliceosome assembly coordination.
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