9219075 Walker There are several different types of protein phosphatases in eukaryotic cells. One class, the type one protein phosphatases (PP1) are thought to be involved in the control of the cell cycle, protein synthesis, membrane functions, and probably many other biochemical activities. In most multicellular organisms there are several different isoforms of PP1. This raises several intriguing questions about the expression, distribution, function, and regulation of these genes and their products. This proposal focuses on a multigene family encoding PP1 in Arabidopsis thaliana. The goal of this research is to determine the pattern of expression and relative abundance of the PP1 genes and proteins, and analyze the regulatory subunits associated with the different PP1 isoforms. Analysis of the PP1 genes of higher plants will enhance our understanding of these important regulatory enzymes in a broader biological context. %%% Control of cellular growth and differentiation is a complex process that requires the integration of many different regulatory circuits. A common mechanism by which cellular processes are regulated is through protein phosphorylation and dephosphorylation. This reversible modification can cause activation, inactivation, or even a subtle modulation of biochemical function. Although protein kinases have been studied extensively, it is evident that protein phosphatases are equally important in controlling the biochemical circuitry that governs a cell's function. Analysis of the protein phosphatase genes of higher plants will enhance our understanding of these important regulatory enzymes in a broader biological context. ***
