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Ca2+/calmodulin-dependent phosphorylation of elongation factor 2.
FEBS Letters
|April 20, 1987
Summary
Calcium ions (Ca2+) trigger the phosphorylation of elongation factor 2 (EF-2), a key protein in protein biosynthesis. This Ca2+-dependent process, potentially mediated by calmodulin, suggests a regulatory role in cellular protein production.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Regulation
Background:
- Protein biosynthesis is a fundamental cellular process.
- Regulation of protein synthesis is crucial for cell function and response to stimuli.
- Calcium ions (Ca2+) act as important intracellular second messengers.
Purpose of the Study:
- To investigate the effect of Ca2+ on protein synthesis in cell-free extracts.
- To identify proteins phosphorylated in a Ca2+-dependent manner.
- To explore the potential role of Ca2+ and calmodulin in regulating protein biosynthesis.
Main Methods:
- Incubation of ribosome-free extracts from rabbit reticulocytes and rat liver with [gamma-32P]ATP and Ca2+.
- Analysis of 32P incorporation into polypeptides using gel electrophoresis.
- Testing the effect of trifluoperazine, a calmodulin antagonist, on phosphorylation.
Main Results:
- 32P was predominantly incorporated into a single polypeptide with an approximate molecular weight of 100,000.
- This polypeptide was identified as elongation factor 2 (EF-2).
- EF-2 phosphorylation was strictly Ca2+-dependent and inhibited by trifluoperazine, suggesting calmodulin involvement.
Conclusions:
- Ca2+/calmodulin-dependent phosphorylation of EF-2 occurs in rabbit reticulocyte and rat liver extracts.
- This phosphorylation event is likely involved in the regulation of protein biosynthesis.
- Identifies a novel regulatory mechanism for protein synthesis mediated by calcium signaling.