Current Topics in Cellular Regulation, Volume 1 presents the fundamental mechanisms involved in the regulation of diverse cellular activities, including the transfer of genetic information, intermediary metabolism, and cellular differentiation. This book discusses the advances in the general area of cellular regulation.Organized into 10 chapters, this volume begins with an overview of the molecular models that attempt to provide the correlation of the kinetic properties of the protein with its structural architecture. This text then examines several aspects of metabolism and of metabolic enzymes that appear to represent adaptations to the need to limit solute concentrations and conserve solvent capacity. Other chapters consider the factors that determine the overall rates of metabolic pathways. This book discusses as well the biosynthetic pathways leading to the branched-chain amino acids. The final chapter deals with the structure and mechanism of action of pyruvate carboxylase.This book is a valuable resource for biologists and biochemists.

List of ContributorsPrefaceConformational Aspects of Enzyme Regulation I. Introduction II. The Symmetry Model III. The Ligand-Induced or Sequential Model IV. Comparison of the Models V. Observed Systems VI. Evaluation VII. Future Developments ReferencesLimitation of Metabolite Concentrations and the Conservation of Solvent Capacity in the Living Cell I. Introduction II. Activated Forms of Intermediates III. Levels of Enzyme Activities IV. Michaelis Constants V. Modulation of Enzyme Activity VI. SummaryThe Role of Equilibria in the Regulation of Metabolism I. Introduction II. The Role of the Lactate Dehydrogenase System in the Control of Gluconeogenesis from Lactate III. The Role of Equilibria in the Alcohol Dehydrogenase System in the Metabolism of Ethanol IV. Extrahepatic Ketogenesis V. Equilibria in the Metabolism of Propionate VI. Summing Up ReferencesRegulation of the Biosynthesis of the Branched-Chain Amino Acids I. Historical Introduction II. Regulation of Metabolite Flow by End-Product Inhibition III. Control of Enzyme Level in the Pathways to the Branched-Chain Amino Acids IV. The Inhibition of Growth of Escherichia coli Strain K12 by Valine ReferencesOn the Roles of Synthesis and Degradation in Regulation of Enzyme Levels in Mammalian Tissues I. Introduction II. Properties of Protein Turnover in Rat Liver III. Theoretical Formulation of a Model for Changing Enzyme Levels in Animal Tissues IV. Control of Synthesis and Degradation of Specific Enzymes V. On Mechanisms Controlling Synthesis and Degradation of Specific Enzymes VI. Concluding Remarks ReferencesThe Regulation of the Biosynthesis of a-1,4-Glucans in Bacteria and Plants I. Introduction II. Properties of the ADP-Glucose:a-1,4-Glucan-4-Glucosyl Transferases of Plants III. Glycogen Accumulation in Bacteria IV. Bacterial ADP-Glucose : a-1,4-Glucan-4-Glucosyl Transferases V. ADP-glucose Pyrophosphorylase (Synthetase) VI. Kinetic Properties of the ADP-Glucose Pyrophosphorylase VII. Physical Properties of the ADP-Glucose Pyrophosphorylases VIII. Genetic Regulation of Glycogen Synthesis in Escherichia coli ReferencesAllosteric L-Threonine Dehydrases of Microorganisms I. Introduction II. Biodegradati ve Dehydrase of Escherichia coli III. Biodegradative Dehydrase of Clostridium tetanomorphum IV. Biosynthetic L-Threonine Dehydrases V. Conclusion ReferencesThe Aspartokinases and Homoserine Dehydrogenases of Escherichia coli I. Two Aspartokinases in Escherichia coli II. The Threonine-Sensitive Homoserine Dehydrogenase of Escherichia coli III. Isolation of a Mutant Lacking the Lysine-Sensitive Aspartokinase Gif 54 and of Revertants Thereof IV. Inhibition Properties of the Aspartokinase and of the Homoserine Dehydrogenase of the Threonine-Excreting Revertants of Gif 54 V. Mutants Lacking Homoserine Dehydrogenase in Escherichia coli B VI. Indirect Evidence That the Threonine-Sensitive Aspartokinase and Homoserine Dehydrogenase of Escherichia coli K12 Are Carried by the Same Molecule VII. Direct Evidence That the Threonine-Sensitive Aspartokinase and Homoserine Dehydrogenase of Escherichia coli K12 Are Carried by the Same Protein VIII. Determination of the Molecular Weight of Aspartokinase I-Homoserine Dehydrogenase I IX. Amino Acid Analysis of Aspartokinase I-Homoserine Dehydrogenase I X. Subunit Structure of Aspartokinase I-Homoserine Dehydrogenase I XI. The Binding of Threonine to Aspartokinase I-Homoserine Dehydrogenase I XII. The Binding of Pyridine Nucleotides of Aspartokinase I-Homoserine Dehydrogenase I XIII. The Effects of Threonine on Aspartokinase I-Homoserine Dehydrogenase I Are Not Due Only to Direct Interaction XIV. Aspartokinase I-Homoserine Dehydrogenase I and the Transconformation Models XV. Demonstration of the Existence in Escherichia coli K12 of a Third Aspartokinase and of a Second Homoserine Dehydrogenase (Aspartokinase II and Homoserine Dehydrogenase II), Two Activities under the Repressive Control of Methionine XVI. Indirect Evidence for a Single Protein Carrying the Aspartokinase and Homoserine Dehydrogenase II Activities in Escherichia coli K12 XVII. The Situation in Escherichia coil B as Opposed to E. coli K12 XVIII. Direct Evidence That Aspartokinase II and Homoserine Dehydrogenase II Activities Are Carried by the Same Protein. Its Molecular Weight and Subunit Structure XIX. Discussion on the Origin of the Two Multifunctional Proteins and of Aspartokinase III. Antigenic Independence of the Three Proteins XX. The Significance of Iso functional and Multifunctional Enzymes in the Regulation of Biosynthetic Pathways ReferencesPyruvate Dehydrogenase Complex I. Introduction II. Composition and Macromolecular Organization III. Regulatory Features IV. Significance of Multienzyme Complexes in Cellular Regulation ReferencesPyruvate Carboxylase I. Introduction. The Discovery and Metabolic Roles of Pyruvate Carboxylase II. Mechanism of Action III. Structure IV. Role of Acetyl-CoA in the Pyruvate Carboxylate Reaction V. Conclusion. Regulation of Pyruvate Carboxylase by Mechanisms Not Related to the Concentration of Acetyl-CoA ReferencesAuthor IndexSubject Index