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Functional properties of phosphorylated elongation factor 2.
U Carlberg1, A Nilsson, O Nygård
1Department of Cell Biology, Wenner-Gren Institute, University of Stockholm, Sweden.
European Journal of Biochemistry
|August 17, 1990
Summary
Phosphorylation of eukaryotic elongation factor 2 (eEF-2) inhibits protein synthesis by reducing its binding affinity to ribosomes. This modification impairs eEF-2
Area of Science:
- Molecular Biology
- Protein Synthesis
- Post-translational Modifications
Background:
- Eukaryotic elongation factor 2 (eEF-2) is crucial for protein synthesis.
- Phosphorylation is a key post-translational modification regulating protein function.
Purpose of the Study:
- To investigate the impact of eEF-2 phosphorylation on its functional activity.
- To elucidate the molecular mechanism by which phosphorylation affects eEF-2 function.
Main Methods:
- Purification of phosphorylated eEF-2.
- Assay of protein synthesis in a rabbit reticulocyte lysate.
- Kinetic analysis of GTP hydrolysis by eEF-2.
- Measurement of dissociation constants for ribosome-eEF-2 complexes.
Main Results:
- Phosphorylated eEF-2 failed to stimulate protein synthesis.
- Phosphorylation did not affect the maximum rate of GTP hydrolysis.
- Phosphorylation significantly reduced the second-order rate constant for GTP hydrolysis.
- Direct measurements confirmed reduced affinity of phosphorylated eEF-2 for ribosomes.
Conclusions:
- Phosphorylation of eEF-2 inhibits its ability to stimulate protein synthesis.
- The inhibitory effect is due to impaired ribosome.eEF-2 complex formation.
- Phosphorylation reduces the affinity of eEF-2 for the ribosome, rather than affecting GTP hydrolysis rate.