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A ribosomal calmodulin-binding protein from Dictyostelium
J Sonnemann1, A Bäuerle, T Winckler
1Fakultät für Biologie, Universität Konstanz, Federal Republic of Germany.
The Journal of Biological Chemistry
|December 5, 1991
Summary
Researchers identified a 22-kDa calmodulin-binding protein in Dictyostelium discoideum, finding it associated with ribosomes. This suggests a role for calmodulin in regulating eukaryotic protein synthesis via calcium ions.
Area of Science:
- Cellular biology
- Molecular biology
- Biochemistry
Background:
- Calmodulin is a key calcium-binding protein involved in cellular signaling.
- Specific calmodulin-binding proteins were previously identified in Dictyostelium discoideum.
Purpose of the Study:
- To identify and characterize specific calcium/calmodulin-binding proteins in Dictyostelium discoideum.
- To elucidate the function and localization of these identified proteins.
Main Methods:
- 125I-calmodulin probe used to identify binding proteins.
- cDNA cloning and screening of a lambda gt11 expression library.
- Antibody production against a lacZ-cDNA fusion protein.
- Sucrose density gradient centrifugation to determine protein association with ribosomal subunits.
Main Results:
- A major 22-kDa calmodulin-binding protein was identified in Dictyostelium discoideum extracts.
- cDNA cloning revealed the 22-kDa protein shares homology with rat ribosomal protein L19.
- The 22-kDa protein was found to be an integral component of the large ribosomal subunit (60S).
Conclusions:
- The 22-kDa calmodulin-binding protein is associated with ribosomes, suggesting a role in protein synthesis regulation.
- Calmodulin may play a physiological role in calcium-mediated regulation of eukaryotic protein synthesis.
- These findings support the hypothesis that calmodulin influences protein synthesis, as suggested by studies with calmodulin antagonists.