The importance of the reversible phosphorylation of proteins, as a mechanism for the control of cell function, is well documented. A strategy has been initiated whereby cloned genes for the catalytic subunits of several protein phosphatases are expressed in cells under the control of a regulatable promoter. Mutant phosphatases with truncated carboxyl and/or amino termini are also being constructed and tested for expression and activity in several cell types. By using this genetic approach, it is proposed that specific phosphorylation events can be markedly blunted or rapidly reversed thus altering the normal protein kinase activated pathways in the cell. The role of protein phosphorylation cascades and their regulation by specific phosphatases can be studied in relationship to cell metabolism, growth, and differentiation. An additional goal of this project is to characterize the repertoire of protein phosphatases in selected cell types using PCR (polymerase chain reaction) and DNA sequencing. This will allow us to estimate the number and nature of protein phosphatases within a specific cell type, as well as potentially identifying new phosphatase genes.
