Function of Protein Phosphatase 2A in Control of Proliferation: Isolation and Analysis of Dominant-Defective Mutants
Annual rept. 15 May 1998-14 May 1999
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 expressed, 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. Previously, we established a functional complementation assay for PP2A-C in the yeast S. cerevisiae and used this system to isolate two dominant-defective mutants in the human PP2A-Calpha gene. We now have generated epitope-tagged forms of the wild-type and mutant alleles and have shown that the epitope-tagged alleles retain biological function in our yeast system. We have also continued the phenotypic analysis of our cell lines expressing PP2A-Calpha alleles, using kinase activation assays to assess growth factor responses in these cell lines. 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