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Mutation of Tyr307 and Leu309 in the protein phosphatase 2A catalytic subunit favors association with the alpha 4 subunit which promotes dephosphorylation of elongation factor-2
- Source :
- Biochemistry. 38(32)
- Publication Year :
- 1999
-
Abstract
- The cellular location and substrate specificity of the catalytic subunit (C) of protein phosphatase 2A (PP2A) depend on its interaction with A and B subunits. The distribution of epitope-tagged wild-type or mutated C subunits was studied by transient expression in COS-7 cells. Wild-type tagged C expressed at low levels formed ABC trimer and AC dimer like the endogenous C. Single mutations of C at the site of phosphorylation (Y307F) or carboxymethylation (L309Q) resulted in recovery of only AC dimer. Double mutation of both residues resulted in association of C with alpha 4 protein (alpha 4), a novel subunit of PP2A, instead of with A and B subunits. Thus, the distribution of C between ABC trimer, AC dimer, and alpha 4C complexes can be affected by modifications of the C-terminal residues. The alpha 4 protein is a homologue of the yeast Tap42 protein that functions downstream of the TOR protein to regulate protein synthesis. Transient overexpression of FLAG-alpha 4 resulted in increased dephosphorylation of elongation factor 2, but had no effect on phosphorylation of either p70S6 kinase or PHAS-I (eIF4E-BP). Signals that affect phosphorylation or methylation of the C subunit of PP2A may promote subunit exchange and direct phosphatase activity to specific intracellular substrates.
- Subjects :
- RFC5
Protein subunit
Trimer
Biology
Transfection
Biochemistry
Dephosphorylation
Bacterial Proteins
Peptide Elongation Factor 2
Leucine
Catalytic Domain
Lectins
Protein biosynthesis
Phosphoprotein Phosphatases
Animals
Protein Phosphatase 2
Phosphorylation
Anion Exchange Resins
Protein phosphatase 2
Chromatography, Ion Exchange
Peptide Elongation Factors
Phosphoproteins
Molecular biology
Precipitin Tests
Elongation factor
Resins, Synthetic
Hemagglutinins
COS Cells
Mutagenesis, Site-Directed
Tyrosine
Peptides
Oligopeptides
Subjects
Details
- ISSN :
- 00062960
- Volume :
- 38
- Issue :
- 32
- Database :
- OpenAIRE
- Journal :
- Biochemistry
- Accession number :
- edsair.doi.dedup.....b8f3a9178a6904521c9cb8438b4b3db7