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Electron microscopic identification of the yeast spliceosome
M W Clark1, S Goelz, J Abelson
1Division of Biology, California Institute of Technology, Pasadena 91125.
The EMBO Journal
|December 1, 1988
Summary
Researchers purified the yeast spliceosome and used electron microscopy to visualize its structure. This revealed the spliceosome as an ovoid disc with a central indentation, confirming its identity through specific tagging.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- The spliceosome is a large and dynamic molecular machine responsible for pre-messenger RNA splicing.
- Understanding the structural and dynamic properties of the spliceosome is crucial for elucidating its function in gene expression.
Purpose of the Study:
- To partially purify the yeast spliceosome.
- To determine the structural characteristics of the spliceosome using electron microscopy.
- To investigate the effect of salt concentration on spliceosome structure and sedimentation.
Main Methods:
- Differential sedimentation in glycerol gradients for partial purification of the yeast spliceosome.
- Transmission electron microscopy (TEM) for visualizing the purified spliceosome particles.
- Specific labeling techniques to confirm the identity of the spliceosome.
Main Results:
- A distinct ovoid disc-shaped particle, identified as the spliceosome, was observed in purified fractions.
- The yeast spliceosome measures approximately 20 x 23.5 nm and features a central indentation.
- Specific tagging and electron microscopy confirmed the identity of the observed particles as spliceosomes.
- A salt-dependent shift in sedimentation rate suggests a change in the particle's size with varying salt concentrations.
Conclusions:
- The study successfully visualized and characterized the structural features of the yeast spliceosome.
- The findings provide insights into the physical dimensions and potential conformational changes of the spliceosome in response to ionic strength.