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Cytoplasmic particles and aminoacyl transferase I activity
The Journal of Cell Biology
|April 1, 1970
Summary
Researchers identified specific rectangular particles in animal and plant cells, but not E. coli. These particles sediment at 19S, coinciding with aminoacyl transferase I activity, suggesting a potential carrier role.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Nucleated cells contain various macromolecular complexes.
- Aminoacyl transferase I plays a crucial role in protein synthesis.
Purpose of the Study:
- To investigate the presence and characteristics of particles in cell supernatant fluids.
- To correlate particle sedimentation with aminoacyl transferase I activity.
Main Methods:
- Electron microscopy was used to visualize particles.
- Sucrose gradient centrifugation was employed to separate cellular components.
- Sedimentation analysis was performed to determine particle size and activity association.
Main Results:
- Specific rectangular particles (100 x 145 A) were observed in nucleated animal and plant cell extracts, absent in E. coli.
- Aminoacyl transferase I activity exhibited two sedimentation peaks (5-7S and 18-20S).
- A 19S rectangular particle directly corresponded to the higher peak of transferase I activity.
Conclusions:
- A distinct rectangular particle exists in eukaryotic cell supernatants.
- This particle is strongly associated with aminoacyl transferase I activity.
- The rectangular particle is proposed as a potential carrier for aminoacyl transferase I.