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Multiple splicing factors are released from endogenous complexes during in vitro pre-mRNA splicing
G C Conway1, A R Krainer, D L Spector
1Cold Spring Harbor Laboratory, New York 11724.
Molecular and Cellular Biology
|December 1, 1989
Summary
Researchers identified large endogenous complexes that interfere with spliceosome isolation. Removing these complexes from nuclear extracts is crucial for studying de novo spliceosomes and isolating splicing factors.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Pre-messenger RNA (pre-mRNA) splicing is a fundamental process in gene expression, occurring within the spliceosome.
- Isolating functional spliceosomes for biochemical analysis is challenging due to contaminating endogenous complexes in nuclear extracts.
Purpose of the Study:
- To investigate the nature of endogenous complexes that hinder spliceosome isolation.
- To develop an improved method for preparing nuclear extracts for spliceosome research.
Main Methods:
- Nuclear extracts were prepared and fractionated to isolate large, fast-sedimenting complexes.
- These complexes were analyzed for the presence of splicing factors and small nuclear ribonucleoproteins (snRNPs).
- The effect of ATP incubation and complex removal on splicing activity was assessed.
Main Results:
- Large endogenous complexes containing multiple snRNPs and heterogeneous nuclear ribonucleoprotein (hnRNP) components were identified.
- These complexes sequester essential splicing factors, preventing the assembly of de novo spliceosomes.
- Removal of these complexes from ATP-preincubated extracts yielded a preparation suitable for isolating native spliceosomes.
Conclusions:
- The identified large complexes represent endogenous spliceosomes that interfere with in vitro splicing studies.
- A method involving the removal of these endogenous complexes enables the isolation of native spliceosomes and facilitates splicing factor fractionation.