A major mechanism by which cells regulate protein function is to place phosphate groups on serine and threonine residues. Though the steady-state level of protein phosphorylation depends on the relative activities of both kinases and phosphatases, a much greater effort has previously gone into the study of the former that the latter . Today, however, there is an increasing appreciation for the role that protein phosphatases play in the dynamic p- cess of protein phosphorylation . To date, there are four major types of protein serine/threonine phosphatase catalytic subunits, designated protein phosphatase type 1, 2A, 2B, and 2C . Each has been identified by the techniques of protein chemistry and enzymology and can be distinguished from one another by their preference for specific substrates as well as their sensitivity to certain acti- tors and inhibitors . Protein Phosphatase Protocols has been assembled in response to the growing interest these enzymes are receiving . The goal of this compilation is to provide a "how-to" experimental guide to aid newcomers as well as s- soned veterans in their research endeavors, thus further contributing towards our ever increasing knowledge of serine/threonine phosphatases . What you have before you contains contributions by many of the current and emerging leaders in the field . To highlight just a few, these chapters c- tain step-by-step information on how to isolate novel phosphatases and re- latory subunits, assay for activity, and generate immunological reagents for both biochemical and biological characterization of these enzymes .

Inhalt
Prokaryotic Protein-Serine/Threonine Phosphatases.- Protein Phosphatase Type 1 and Type 2A Assays.- Analyzing Gene Expression with the Use of Serine/Threonine Phosphatase Inhibitors.- Inhibitor-1, a Regulator of Protein Phosphatase 1 Function.- I1 PP2A and I2 PP2A.- Control of PP1 Activity Through Phosphorylation by Cyclin-Dependent Kinases.- Regulation of Neuronal PP1 and PP2A During Development.- PTPA Regulating PP2A as a Dual Specificity Phosphatase.- Microinjection and Immunological Methods in the Analysis of Type 1 and 2A Protein Phosphatases from Mammalian Cells.- Use of Immunocomplexed Substrate for Detecting PP1 Activity.- The Biochemical Identification and Characterization of New Species of Protein Phosphatase 1.- The Relationship Between Insulin Signaling and Protein Phosphatase 1 Activation.- Analysis of the Isoforms of Protein Phosphatase 1 (PP1) Isoforms with Polyclonal Peptide Antibodies.- Expression of Mouse Protein Phosphatase 2C in Eschericia coli and COS 7 Cells.- Expression of Functional Protein Phosphatase 1 Catalytic Subunit in E. coli.- Protein Phosphatase 2A and Protein Phosphatase X Genes in Arabidopsis thaliana.- Separation of Protein Phosphatase Type 2C Isozymes by Chromatography on Blue Sepharose.- Chromatographic Isolation of PP2A from Limulus Lateral Eyes.- Purification and Assay of the Ptc/Tpd1 Protein Phosphatase 2C from the Yeast Saccharomyces cerevisiae.- Molecular Cloning of Protein Phosphatase Type 2C Isoforms from Retinal cDNA.- Analysis of Protein Interactions Between Protein Phosphatase 1 and Noncatalytic Subunits Using the Yeast Two-Hybrid Assay.- Identifying Protein Phosphatase 2A Interacting Proteins Using the Yeast Two-Hybrid Method.- Protein Phosphatase 2A Regulatory Subunits.- Synthetic Lethal Screening in Protein PhosphatasePathways.- The Search for the Biological Function of Novel Yeast Ser/Thr Phosphatases.