Function of Protein Phosphatase 2A in Control of Proliferation: Isolation and Analysis of Dominant-Defective Mutants
Annual rept. 15 May 97-14 May 98
BROWN UNIV PROVIDENCE RI
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Reversible protein phosphorylation plays a crucial role in the circuitry controlling diverse cellular processes, and the activities of phosphorylating and dephosphorylating enzymes must be carefully balanced in normal cells. It is well documented that many of these enzymes are constitutively expressed1 but their activities are tightly regulated by a variety of post translational mechanisms. In the case of the serinethreonine-specific protein phosphatase 2A PP2A, a catalytic subunit is bound by two regulatory subunits designated A and B. We have established a functional complementation assay in the yeast S. cerevisiae and have used this assay to isolate two dominant-defective mutations in a human PP2A catalytic subunit gene, via oligonucleotide-mediated site-directed mutagenesis. We have expressed the mutant and wild-type catalytic subunit genes in mammalian cells, and have initiated our characterization of the effects of these proteins on endogenous PP2A activity, as well as cellular physiology. These studies will thus increase our understanding of PP2A function in the regulation of proliferation and malignant transformation, and will yield important information about structure-function relationships in the PP2A catalytic and regulatory subunit proteins.
- Genetic Engineering and Molecular Biology
- Medicine and Medical Research